Hello all, Just thumbing through my Hornady reloading manual and came across the 7.5 Swiss cartridge. I've looked at this case numerous times, but that was before I was a member of the forum. Now that I can bounce my ideas of very knowledgable people, I thought I'd ask if anyone on the forum has ever done any work with the 7.5 Swiss cartridge, as fas as wildcats in .257cal - .284cal ? Dimensions look like it would be a good parent case just necked down, without any improvements. If you were to give it an Ackley facelift, it may give approx. a 7% to 10% improvement (pure speculation) ? Also without a rebated rim to work (fight) with, it's likely little to no time and effort would be required getting it to feed properly. With case dimensions being what they are, BUT shorter than the 06 case, a standard length action would be required for seating depth versatility, and optimal cartridge OAL, regardless of caliber. I was thinking it would make a very efficient, very versatile 25x55 Swiss AI. It would have more capacity than the 257Rob, but less than the 25-06. A 6.5 or 7mm would also be very versatile, since any bullets in those 2 bore sizes could be seated to depths that never impinge on powder space. Just my thoughts, I wish I had some cases to play around with, and give some more technical specs, but I can't at this time. Being an oddball cartridge, the number of people with experience using it, may be pretty small. Whether or not it's a worthwhile project is purely up to the individual who just wants something different. It may make for some interesting conversation...guess we'll see.
Elkhamr
Elkhamr,
We shoot the K31. As it is that 7.5x55 already is an impressive performer. A real mover. Personally I would not neck it down smaller than 6.5mm but of course wildcatting has no brakes. Most of the ammunition and used cases have been secured in a container for a move to another venue and it may not be possible to locate an empty case immediately. Nevertheless, a search shall be conducted in Colorado and if a case turns up it is yours.
We shoot the K31. As it is that 7.5x55 already is an impressive performer. A real mover. Personally I would not neck it down smaller than 6.5mm but of course wildcatting has no brakes. Most of the ammunition and used cases have been secured in a container for a move to another venue and it may not be possible to locate an empty case immediately. Nevertheless, a search shall be conducted in Colorado and if a case turns up it is yours.
MusgraveMan thank you for the reply, and thank you for offering to try locating a piece of brass. I've always thought the cartridge was a gem, and has alot of potential in modern rifles. If you were to build a 7.5x55 for open country deer hunting, as well as mountainous terrain for elk, what do you feel would be an appropriate barrel length to wring the most out of this cartridge? What I like about the case in the virgin state is, it's length would allow for very versatile seating depth for all .308 hunting bullets, and possibly even the real high BC bullets. If we look at the case volume of the 30 TC, which is a real performer for it's capacity, and compare it to the Swiss, the potential with modern powders and higher BC bullets in the Swiss with appropriate barrel length could really make it shine. I keep my eye out at gun shows for 7.5x55 Swiss and 376 Steyr brass to work with, but where I live these rounds are unheard of. Another idea I had was to build it on a single shot platform. There would be no magazine length constraints, and the action being so short would allow for a longer barrel, and still keep the weight down fairly low. Anyway just a thought, and thanks again for your reply and Ideas. Glad someone with field experience was able to shed some light on this gem.
After a few searches that turned up very vague information about any 7.5x55 based wildcats, I came across some more vague info, about some guys developing Swiss based wildcats on the Firing Line Forum. I tried registering to the forum to access the info, but was unsuccessful, I kept getting bounced around from page to page, and never did get registered. I'll keep at it, and maybe someone else will churn up some good solid info.
As said before - in my my field of reference that case may merit necking down to 6.5mm but not smaller. I know many wildcatters do not really mind about throat erosion as long as they can get the best speed out of it with light-weight bullets. Let me go back a ways and I'll return to modifying this excellent case that had used perfect mathematics to already make it simply very efficient.
There is another field of wildcatting which almost fails to meet the first-order understanding of the term of wild abandon - and that is dedicating a rifle and cartridge to a certain task. Wildcatting in its essence is about "free thinking" - even towards slowing down a particular bullet for a particular task. I asked a question in another thread here because that particular subject under discussion had touched on a long time thought I've had and I casually mentioned my reason for liking a particular post. CrookedCreek picked up on that and started a thread about my humble "bushbuck rifle", and just look where we have gone with that.
I have only shot two rifles in my life which I did not like. The first was Jeff Cooper's one-off .460 Guns&Ammo wildcat and the other was some Savage in .22-250. Nothing was really right in the latter but mainly it was the off-hand un-balance of the rifle, and roughness of the action. The stock design for Cooper's idea which he brought to Africa was sadly nowhere near suitable for the amount of recoil it had. That rifle needed the Bavarian style stock, but Jeff Cooper having been Jeff Cooper would rather have died seven deaths before accepting such advice from us. His wildcat died too. Like Jack Lott he was disgusted with the .458 Win Mag after in a previous visit to Africa, 8 shots from his .458 WM did not even put his Cape Bufallo down and his PH putit out of its misery it with his .375 H&H. To this day Winchester was not interested in this problem and Cooper decided to build his own buffalo rifle and cartridge - but the typical straight line American "Safari" profile for the stock is not clever for that amount of recoil.
So I like most almost every rifle I have shot. Then one day you shoot a rifle cartridge combination which truly leaves a lasting impression on you - maybe a few even, which many years after having pulled its trigger and emptied its magazine you will remember the satisfaction it had caused in its balance, and at or on the target performance. To me the 7.5x55 Schmidt-Rubin from the K-31 is one of those. (The others are the 8x68 Schuler; 7x64 Brenneke and equalled again by the .280 Remington; 7mm Rem Magnum; .338 Win Mag - although in Africa there is only one single use for it; 9.3x62 Bock and the .416 Rigby, and my Kentucky .50 muzzle loader with top loads). Every time I shoot the Rubin in Colorado the impression that this is something special is reaffirmed.
The Swiss will lend itself to necking down to 7mm, and possibly also to 6.5mm dedicated to 154gr bullets at 62,000 with original GP-11 cases. In 7mm I would dedicate it to 170gr. In standard form it will accept US designated .308" bullets as is. I shot in military competitions against the Swiss Army/Air Force team using the K-31. The stock military rifle is simply very accurate. Impressively so.
My own opinion for a modification? An "Ackley improved" profile to 8mm and even 9.3mm. Do the figures for that and see what you get.
In Europe, to obtain official approval by the C.I.P. (and in South Africa by the SABS Standards Bureau) the cartridge and every single rifle to fire it and which is to be sold to the public has to be fired at 125% of the load that approval is applied for with no measurable plastic deformation. That pressure figure for the Swiss is 68,000+ psi.
Hornady as well as Privy Partizan sells 7.5x55 ammunition in the US.
There is another field of wildcatting which almost fails to meet the first-order understanding of the term of wild abandon - and that is dedicating a rifle and cartridge to a certain task. Wildcatting in its essence is about "free thinking" - even towards slowing down a particular bullet for a particular task. I asked a question in another thread here because that particular subject under discussion had touched on a long time thought I've had and I casually mentioned my reason for liking a particular post. CrookedCreek picked up on that and started a thread about my humble "bushbuck rifle", and just look where we have gone with that.
I have only shot two rifles in my life which I did not like. The first was Jeff Cooper's one-off .460 Guns&Ammo wildcat and the other was some Savage in .22-250. Nothing was really right in the latter but mainly it was the off-hand un-balance of the rifle, and roughness of the action. The stock design for Cooper's idea which he brought to Africa was sadly nowhere near suitable for the amount of recoil it had. That rifle needed the Bavarian style stock, but Jeff Cooper having been Jeff Cooper would rather have died seven deaths before accepting such advice from us. His wildcat died too. Like Jack Lott he was disgusted with the .458 Win Mag after in a previous visit to Africa, 8 shots from his .458 WM did not even put his Cape Bufallo down and his PH putit out of its misery it with his .375 H&H. To this day Winchester was not interested in this problem and Cooper decided to build his own buffalo rifle and cartridge - but the typical straight line American "Safari" profile for the stock is not clever for that amount of recoil.
So I like most almost every rifle I have shot. Then one day you shoot a rifle cartridge combination which truly leaves a lasting impression on you - maybe a few even, which many years after having pulled its trigger and emptied its magazine you will remember the satisfaction it had caused in its balance, and at or on the target performance. To me the 7.5x55 Schmidt-Rubin from the K-31 is one of those. (The others are the 8x68 Schuler; 7x64 Brenneke and equalled again by the .280 Remington; 7mm Rem Magnum; .338 Win Mag - although in Africa there is only one single use for it; 9.3x62 Bock and the .416 Rigby, and my Kentucky .50 muzzle loader with top loads). Every time I shoot the Rubin in Colorado the impression that this is something special is reaffirmed.
The Swiss will lend itself to necking down to 7mm, and possibly also to 6.5mm dedicated to 154gr bullets at 62,000 with original GP-11 cases. In 7mm I would dedicate it to 170gr. In standard form it will accept US designated .308" bullets as is. I shot in military competitions against the Swiss Army/Air Force team using the K-31. The stock military rifle is simply very accurate. Impressively so.
My own opinion for a modification? An "Ackley improved" profile to 8mm and even 9.3mm. Do the figures for that and see what you get.
In Europe, to obtain official approval by the C.I.P. (and in South Africa by the SABS Standards Bureau) the cartridge and every single rifle to fire it and which is to be sold to the public has to be fired at 125% of the load that approval is applied for with no measurable plastic deformation. That pressure figure for the Swiss is 68,000+ psi.
Hornady as well as Privy Partizan sells 7.5x55 ammunition in the US.
Attachments
MM you are a lucky man, having access to the firearm and cartridges, and all the sources you have to collect information makes it all the more rich of an experience for you. "We have what we have" here in the U.S. and if we want something different to what our manufacturers provide, we have to think outside the box and build it ourselves. I don't mind doing that though, because in the end the learning and knowledge gained throughout the proccess, is a "forever" type of experience. Once that knowledge is gained, it makes talking with experts like yourself and other forum members that much more of a rich experience. Arguments could be made either way whether that this is a worthless endeavor and that there is already enough cartridges out there to fill any niche. I believe that's true BUT, if we ever stop thinking of ways to improve something, then this gets to be a boring stagnant sport for the average shooter/handloader. It's pretty hard for me to get all revved up about going down, and loading a bunch of 30-06 rounds. I like sticking cases in different dies and seeing what I can make, it's fun and it inspires a person to imagine how it will perform as we thumb through reloading manuals comparing it to other cases. My thinking with the Swiss, is that it is a case that could make an entire line of efficient, light recoiling cartridges from 257-9.3cal. The performance is already built into that case, it already runs at 60,000plus, changing the bullet diameter only unlocks "more of a good thing" in my mind, and opens up a whole new to "us" platform. RWS is another manufacturer I've posted on looking for info and drawings to work from. The Euro cases are just better, there's a reason they can safely load them to the kinds of pressures they do, the works been done already, it just takes open minds to go get those cases and work with them. About you Bushbuck rifle, I followed that entire post and learned alot, it's all technical scientific data that is tried and true, the reson it was so interesting to me is because I have a unique situation coming up this next hunting season where I need a cartridge with low muzzle blast, low velocity, but still capable of anchoring Whitetails with shoulder shots BUT not ruining a bunch of meat. The animals HAVE to drop on the spot or within 20yds because of surrounding houses and properties. I can't shoot some firebreathing magnum for this, it has to be a low key operation, or it's off the table. That's for another post but wanted you to see why your bushbuck rifle post really appealed to me and fit my situation. I thought of naming mine "Urban Deerslayer"....pretty fitting name.
"Arguments could be made either way whether that this is a worthless endeavor and that there is already enough cartridges out there to fill any niche. I believe that's true BUT, if we ever stop thinking of ways to improve something, then this gets to be a boring stagnant sport for the average shooter/handloader. It's pretty hard for me to get all revved up about going down, and loading a bunch of 30-06 rounds."
I have been your signature boring .308W / 30-06 user/hunter for 50 years. My dad's Parker Hale 30-06 and my Musgrave .308W killed every type of elk size game with such boring one-shot regularity for many years. Then I wanted to give the Musgrave a rest because the factory closed down and that particular model was becoming a bit of an icon. Over two years I searched to build up a truly matched set SAKO Model 85 Hunters in .375 H&H / 30-06 / .270W / 243W - and found the .375 was doing most of the work, followed by the 30-06.
The .270W was merely a duplicate of the .308W on deer size game at longer distances and not nearly as good on big game like kudu and wildebeest at shorter distances due to its lightweight 150gr bullets. The .243W is regarded as a varmint cartridge out here and I used that successfully on jackal and caracal culling.
That beautiful set of SAKOS were a covey of very sexy mistresses - and I realised that much in the end, so I sold the set. (SAKOS are to this day a very good financial investment, by the way).
I needed change, and then I moved to the US and wanted a true US born rifle and cartridge - so a 30-30 Marlin was it. Then I read about the Pennsylvania rifle and built myself a Kentucky .50. Then I learned about the .280 Remington, and Ruger was the only remaining US manufacturer and that was a good find - an industry neglected cartridge and the equivalent of the 7x64 Brenneke when loaded properly. Everything the .270W was punted to be but could not achieve.
Back home I had given my Musgraves (.308W and 30-06) to my two sons and turned my old Lee Enfield .303 into a very pleasing big game getter - another rifle and cartridge which is a very satisfying shooter and hunter. Now I am about to get an old Mauser 8x57 and it will also become a beautiful looking killer.
Then came the wildcat free thinking about a heavy, slow mover for exactly the same reasons you mention - it almost gave me the creeps to read your scenario. True bushbuck surroundings. The .35-30/30 wildcat plan is almost complete thanks to 150 or so posts from experts in that thread.
I still need a heavy bullet, slow mover, for camp meat in the Mozambique wilderness as presently I carry the .416 Rigby there because it is wild country with lots of wild stuff around. BUT: the .416 is so much gun it makes the hunter virtually fearless and maybe even careless as it can take care of any situation you can get into even with incomplete situational awareness. That is the crux: If I want to stay the alert hunter I have been while I am getting older I can not allow myself to insure my life by simply having a strong rifle in my hands all the time.
My Mozambique wildcat is going to be a Lee Enfield No.4 Mk.1,shooting a 9.3x55 wildcat based on the .303 case. That will again humble me some to again be a better tracker and listener and observer - a better hunter again - to stay out of trouble while looking for bushbuck or a young sable bull for camp meat. It must however be able to get a bullet into the brain of a fool charging buffalo cow or hippo or trap-injured lion because one can not always avoid that. Free thinking.
I have been your signature boring .308W / 30-06 user/hunter for 50 years. My dad's Parker Hale 30-06 and my Musgrave .308W killed every type of elk size game with such boring one-shot regularity for many years. Then I wanted to give the Musgrave a rest because the factory closed down and that particular model was becoming a bit of an icon. Over two years I searched to build up a truly matched set SAKO Model 85 Hunters in .375 H&H / 30-06 / .270W / 243W - and found the .375 was doing most of the work, followed by the 30-06.
The .270W was merely a duplicate of the .308W on deer size game at longer distances and not nearly as good on big game like kudu and wildebeest at shorter distances due to its lightweight 150gr bullets. The .243W is regarded as a varmint cartridge out here and I used that successfully on jackal and caracal culling.
That beautiful set of SAKOS were a covey of very sexy mistresses - and I realised that much in the end, so I sold the set. (SAKOS are to this day a very good financial investment, by the way).
I needed change, and then I moved to the US and wanted a true US born rifle and cartridge - so a 30-30 Marlin was it. Then I read about the Pennsylvania rifle and built myself a Kentucky .50. Then I learned about the .280 Remington, and Ruger was the only remaining US manufacturer and that was a good find - an industry neglected cartridge and the equivalent of the 7x64 Brenneke when loaded properly. Everything the .270W was punted to be but could not achieve.
Back home I had given my Musgraves (.308W and 30-06) to my two sons and turned my old Lee Enfield .303 into a very pleasing big game getter - another rifle and cartridge which is a very satisfying shooter and hunter. Now I am about to get an old Mauser 8x57 and it will also become a beautiful looking killer.
Then came the wildcat free thinking about a heavy, slow mover for exactly the same reasons you mention - it almost gave me the creeps to read your scenario. True bushbuck surroundings. The .35-30/30 wildcat plan is almost complete thanks to 150 or so posts from experts in that thread.
I still need a heavy bullet, slow mover, for camp meat in the Mozambique wilderness as presently I carry the .416 Rigby there because it is wild country with lots of wild stuff around. BUT: the .416 is so much gun it makes the hunter virtually fearless and maybe even careless as it can take care of any situation you can get into even with incomplete situational awareness. That is the crux: If I want to stay the alert hunter I have been while I am getting older I can not allow myself to insure my life by simply having a strong rifle in my hands all the time.
My Mozambique wildcat is going to be a Lee Enfield No.4 Mk.1,shooting a 9.3x55 wildcat based on the .303 case. That will again humble me some to again be a better tracker and listener and observer - a better hunter again - to stay out of trouble while looking for bushbuck or a young sable bull for camp meat. It must however be able to get a bullet into the brain of a fool charging buffalo cow or hippo or trap-injured lion because one can not always avoid that. Free thinking.
MM, I HOPE I didn't sound as if I don't give credit/respect or pay homage to the 30-06 or 308 and varient or offspring of those 2 fine cartridges, honestly nothing can be further from the truth. Without them we would never be where we are today, and those 2 cartridges are the backbone, and workhorses of the American hunter and hunters/riflemen abroad depending on game being hunted. I also am a big fan of the 8mm. When building my 8mm wildcat, I didn't care so much about there not being a wide selection of bullet weights available. I wanted a single purpose built rifle for elk, and wanted it to deliver a 200gr bullet with substantial authority at ranges to 300yds.. I chose the 200gr Accubond, and the 7mm Dakots case, Rem 721 action. So far it has met my expectations and then some. I really need to get it hooked up to some pressure trace equipment, to see where I'm at as far as pressures. I don't know if I'm anywhere close to the designed pressures of the 7mmDakota case. There may be more potential or I may be at a safe max...don't know at this time. I thought about paying someone from the forum, to run some pressure tests on the rifle, and give me their opinions, thoughts, ideas. or changes needed if any. Anyway, that's another deal all together. So back to your bushbuck thread, I wanted to ask some questions as people were adding valuable experience and info, but didn't want to disrupt the evolution of the thread. I'm hoping the same folks will give their opinions/field experience, when it comes time to get my project up and running. The 2 situations as you say are eerily similar, except I don't have dangerous life threatening situations around every blade of grass like you encounter daily. I will just have a bunch of nonhunters/anti anything outdoors, scoffing at me across the fences. I'm thinking my 338 Marlin Exp. slowed way down, with a bullet yet to be determined from members input here, should work really well. It needs to be extremely consistant accuracy wise, since I'm not the only one who will be using it to harvest deer with 1 shot kills. That's just one idea since I have the rifle on hand, and would lend itself to being loaded down.
Elkhamr, where the 35-30/30 will be used there is nothing dangerous - it will be on SA unfenced properties and not in Mozambique. The biggest risk is a lung shot which on all Africa game is poor shot placement and the bushbuck is a gutsy little critter having an ego as big as a buffalo since he has horns designed to impale. Even with us humans the more ability our spears contain the more guts and ego we display, is it not? God forbid that the heartbreakingly docile eland one day assumes that fighter's attitude the little bushbuck has. The eland is heavier than a Cape buffalo and a 1,000 times more agile. I have seen 2,000 lb bulls clear an eight foot fence from simply standing next to it. As it dies the eyes shed big tears at the same time the sphincter muscle relaxes and we like to believe that it merely is sinusoidal fluid being released.Mozambique is where I plan the 9.3x55mm only using local PMP brass as these are of measurably thicker gauge than anything else. For the .303 and .308W case volume:neck diameter that is very good. We are in some spat with PMP presently as they sell their brass and ammunition cheaper overseas than what we suddenly have to pay for it. Some bean counters at PMP have decided that if local users want the best then we have to pay a premium for it. The other good brass out here is from Lapua, and the Hornady is also good. PMP primers are in a class of their own but Remington is the next option we prefer - and Sellier&Bellot is the favourite with the mass reloaders like my sons who shoot in the defense handgun competitions.
The .308W will always be the goto big game cartridge out here followed by the 30-06/7x57/7x64/.303 as they are the cleanest killers of all. Having been using the .308W and 30-06 for 50 years I also want something now which is not "more of the same" - even while full knowing that once the bullet leaves the muzzle the size and shape of the case has nothing at all to do with its success on game. From there on ONLY its design structure (to be able, by virtue of its mass - the amount of matter it contains - to withstand the release of kinetic energy into itself as it slows down) will determine its success or failure to stay intact and cleanly punch through the heart's main protective cage of shoulder bone, sinew and muscles and possibly a rib, to cut the heart and then force its way out the similar opposite side without having expanded more than about 1.5x calibre - and never more than 2x. Of course for calibres thicker than .35" no expansion at all is needed.
There is a distinct move by the younger generation hunters out here towards heavier, slower bullets in all the calibres mentioned above, and particularly the magnums. The evidence to support that thinking is simply too obvious to ignore. Since the advent of range finders there is no aiming problem with a rainbow trajectory - in fact there has never been such a thing as a flat shooting calibre in any case.
Elkhamr, this is an open invitation to please bring your questions to the bushbuck thread - I am already clearing that with the OP (CrookedCreek) as it is very closely related. Great respect for your ethics, sir.
MM thank you very much for the invitation to bring my questions to the Bushbuck rifle post. Thank you also for recognizing my ethics, even though our situations are very similar, one question from me, could have pointed the flow of info in a completely different direction and disrupted peoples train of thought. I saw it as a time to learn and not talk I guess you could say. I want to read everything again without distractions, and look at all the links to info referenced again. I'm sure some of my questions can be answered, therefore not rehashing any info or wasting peoples time. I'll write my questions down so it will help keep my train of thought, so info will flow smoothly as in your post. I'm really looking forward to others suggestions for bullets in the 338 Marlin Exp. at lower than normal start velocities. So I'm hoping to get some time thursday to sit down and compile some thoughts, ideas , questions, then possibly by weeks end I can put up a new thread. If enough of my questions are answered through reading then I'll hold off on a new thread and do some testing before I start asking questions and again wasting time rehashing info. Thanks again MM, take good care out there !
Hello fellas, after much thought, and without hijacking MMs & CCs Bushbuck Rifle post, Maybe the best approach would be to just present the hunting scenario here, and let everybody including the Moderators decide if a new thread is warrented. I'll wait to hear back from a few of you before going any further...thanks.
Interesting and polite discourse.
The 7.5x55 SR would be a much more popular cartridge for wildcatting, were it not for the odd head size and the fact that no other rifle is easily converted to its use, aside from what it was originally offered in. Most rifle cartridges, including wildcats, are based on a handful of case head sizes. There are plenty of exceptions, but the majority of cases are going to be .378", .473", .532", .535" or .537". Among the .532" case heads, you are now finding both belted (300H&H) and non-belted rounds (375 Ruger). The two largest families of cartridges, based on the 8x57 or 30-'06, can actually be considered two branches of the same family. The 7.5x55 doesn't fit in any of these categories.
Now, none of that matters at all, if you're chambering it in a single-shot action, but there is only so much of a market for shooters of single-shot rifles. The idea of designing a cutter to reduce the rim (while simultaneously deepening the extractor groove?), resulting in a rebated case head of .473" diameter would allow the fatter case body of the 7.5x55 to be fed through many common bolt-action rifles, with some massaging of the feed rails and magazine well. It would probably make the most sense to concede capacity and go with a single-stack design.
Although the 7.5x55 is shorter, the fatter case body would offset some of the capacity differences, resulting in a round that is probably very close to the 30-'06, in terms of velocity. And this is where the design of this cartridge, for wildcatting starts to look suspiciously like the 284 Winchester. With its fatter case body and rebated case head, the 284 Win is 2.170" long, while the 7.5x55 is 2.190" in length. Looked at in this light, perhaps the designer of the 284 Winchester was attempting to emulate the 7.5x55, but decided to go with a .500" case body, instead of the slightly smaller .493" of the much older round?
To MM's earlier point, the smallest diameter such a case would be well-intended for might be 6.5mm, and the 6.5x284 is an exceptional round on the benchrest circuit! How could a 6.5x55 SR be any less?
Pretty much all of the really GOOD wildcatting ideas have been done, repeatedly. I'm not saying the 7.5x55 case is a poor choice for wildcatting; if a good quantity of Boxer-primed brass was available, I'm confident a whole family of 'cats could be designed, from 6mm on up to 35 caliber. The challenge is the funky case head size, and the fact that IF you made them into a rebated case head style, it would basically just be the 284 Winchester all over again.
How deep is your wallet and how bright is that twinkle in your eye? That's what wildcatting always boils down to, anyway...it's not like the end product is going to be anything new or even better, for the most part.
The 7.5x55 SR would be a much more popular cartridge for wildcatting, were it not for the odd head size and the fact that no other rifle is easily converted to its use, aside from what it was originally offered in. Most rifle cartridges, including wildcats, are based on a handful of case head sizes. There are plenty of exceptions, but the majority of cases are going to be .378", .473", .532", .535" or .537". Among the .532" case heads, you are now finding both belted (300H&H) and non-belted rounds (375 Ruger). The two largest families of cartridges, based on the 8x57 or 30-'06, can actually be considered two branches of the same family. The 7.5x55 doesn't fit in any of these categories.
Now, none of that matters at all, if you're chambering it in a single-shot action, but there is only so much of a market for shooters of single-shot rifles. The idea of designing a cutter to reduce the rim (while simultaneously deepening the extractor groove?), resulting in a rebated case head of .473" diameter would allow the fatter case body of the 7.5x55 to be fed through many common bolt-action rifles, with some massaging of the feed rails and magazine well. It would probably make the most sense to concede capacity and go with a single-stack design.
Although the 7.5x55 is shorter, the fatter case body would offset some of the capacity differences, resulting in a round that is probably very close to the 30-'06, in terms of velocity. And this is where the design of this cartridge, for wildcatting starts to look suspiciously like the 284 Winchester. With its fatter case body and rebated case head, the 284 Win is 2.170" long, while the 7.5x55 is 2.190" in length. Looked at in this light, perhaps the designer of the 284 Winchester was attempting to emulate the 7.5x55, but decided to go with a .500" case body, instead of the slightly smaller .493" of the much older round?
To MM's earlier point, the smallest diameter such a case would be well-intended for might be 6.5mm, and the 6.5x284 is an exceptional round on the benchrest circuit! How could a 6.5x55 SR be any less?
Pretty much all of the really GOOD wildcatting ideas have been done, repeatedly. I'm not saying the 7.5x55 case is a poor choice for wildcatting; if a good quantity of Boxer-primed brass was available, I'm confident a whole family of 'cats could be designed, from 6mm on up to 35 caliber. The challenge is the funky case head size, and the fact that IF you made them into a rebated case head style, it would basically just be the 284 Winchester all over again.
How deep is your wallet and how bright is that twinkle in your eye? That's what wildcatting always boils down to, anyway...it's not like the end product is going to be anything new or even better, for the most part.
7.5 x54.5 Swiss is interesting. Iirc, it and the French 7.5 both use .308" diameter bullets.
The x55 Swedish has a slightly larger diameter than the x57mm Commission and, 06 families of cases.
The x54.5 Swiss is slightly larger again.
That body diameter is slightly larger than the 7.62x54 Mosin Nagant, and if the rims are turned off, Donelly claims that 7.62x54 brass can be reformed to make slightly short necked Swiss cases. I think that case head bulging would be nasty, if that was tried for full pressure loads.
In the factory/ military case, capacity is about 63 grains of water, so mid way between the .303, .308, x57mms and the x64mm, 06 cases.
Back in the 1950s and 60s, a Dr Arch developed loads for a series of wildcats from .257" upwards, based on the X55mm Swedish case, blown out a little. Ackley's books list loading data. IIRC, Dr Arch was interested in heavy bullets. Dr Arch's other well known project was the .378 Weatherby necked down to .30 for 1,000 yard target shooting.
Arch's work will give you some idea of what the wildcats will look like. For performance, given the same operating pressures, bullet weight and calibre, and barrel length, they'll be roughly mid way between .308/x57mm based cases and 06 based cases.
Slightly larger case head internal diameter will mean approximately 50% more backthrust against the bolt for any given peak pressure, possibly giving slightly more dispersion of the groups compared to .470" diameter cases. This last point is based on the reasoning given in Harold Vaughn's book "rifle accuracy facts".
To put that "slightly more dispersion" into its proper context, Case head internal diameter is about the same size of .284 Win, or the belted mag cases, but isn't anywhere near that of the .404 Jeffery derived short action and super mags, so assuming that everything else is equal, it won't shoot any worse than they do.
The marketing claim ( repeated by far too many gunzine writers) that a larger case diameter "is a proven bench rest principle/concept", is an egregious lie. The big reductions in bench rest group size accompanied reductions in case head diameter and backthrust, with the move to cases based on the .222 and the x39mm soviet (Mannlicher) head sizes.
I had a good chuckle at a 1960 s edition of Smith and Smith's " Small Arms of the world" which goes to great lengths to praise and brown nose any opinions of the united state military's top brass, and to disparage anything which seems to conflict with that prevailing received and nationalistically determined wisdom, which in that edition was that the .30-06 was the bestest possible military rifle round Evah... and as far as the 7.62x51 or anything else resembled the 06, it could probably be tolerated as second bestest.
The book lacks clear titles for which gun is being written about, but does have spurious "special note"s on almost every page. One, on the 7.62x39, says it appeared that the soviets were using the 7.62x54R anywhere that accuracy was required... The implication being that anything other than .30-06 (and when it came to pistols, .45 ACP) or that deviated in any way from them, just had to be inherently "inaccurate".
Those were the days before the .22 and 6mm PPC were developed on the x39mm case.
The later editions of "Small Arms of the World" that were edited by Ezell, are far clearer and more objective. The Ezells avoid the contradictions that inevitably follow from the Smiths' apparent use of similar criteria for truth and validity to those famously elaborated in the pronouncements of both the late united state Supreme Court Justice Oliver Wendell Holmes, and of soviet Comissar Lysenko.
Back to x54.5mm Swiss based wildcats. Happy experimenting!
The x55 Swedish has a slightly larger diameter than the x57mm Commission and, 06 families of cases.
The x54.5 Swiss is slightly larger again.
That body diameter is slightly larger than the 7.62x54 Mosin Nagant, and if the rims are turned off, Donelly claims that 7.62x54 brass can be reformed to make slightly short necked Swiss cases. I think that case head bulging would be nasty, if that was tried for full pressure loads.
In the factory/ military case, capacity is about 63 grains of water, so mid way between the .303, .308, x57mms and the x64mm, 06 cases.
Back in the 1950s and 60s, a Dr Arch developed loads for a series of wildcats from .257" upwards, based on the X55mm Swedish case, blown out a little. Ackley's books list loading data. IIRC, Dr Arch was interested in heavy bullets. Dr Arch's other well known project was the .378 Weatherby necked down to .30 for 1,000 yard target shooting.
Arch's work will give you some idea of what the wildcats will look like. For performance, given the same operating pressures, bullet weight and calibre, and barrel length, they'll be roughly mid way between .308/x57mm based cases and 06 based cases.
Slightly larger case head internal diameter will mean approximately 50% more backthrust against the bolt for any given peak pressure, possibly giving slightly more dispersion of the groups compared to .470" diameter cases. This last point is based on the reasoning given in Harold Vaughn's book "rifle accuracy facts".
To put that "slightly more dispersion" into its proper context, Case head internal diameter is about the same size of .284 Win, or the belted mag cases, but isn't anywhere near that of the .404 Jeffery derived short action and super mags, so assuming that everything else is equal, it won't shoot any worse than they do.
The marketing claim ( repeated by far too many gunzine writers) that a larger case diameter "is a proven bench rest principle/concept", is an egregious lie. The big reductions in bench rest group size accompanied reductions in case head diameter and backthrust, with the move to cases based on the .222 and the x39mm soviet (Mannlicher) head sizes.
I had a good chuckle at a 1960 s edition of Smith and Smith's " Small Arms of the world" which goes to great lengths to praise and brown nose any opinions of the united state military's top brass, and to disparage anything which seems to conflict with that prevailing received and nationalistically determined wisdom, which in that edition was that the .30-06 was the bestest possible military rifle round Evah... and as far as the 7.62x51 or anything else resembled the 06, it could probably be tolerated as second bestest.
The book lacks clear titles for which gun is being written about, but does have spurious "special note"s on almost every page. One, on the 7.62x39, says it appeared that the soviets were using the 7.62x54R anywhere that accuracy was required... The implication being that anything other than .30-06 (and when it came to pistols, .45 ACP) or that deviated in any way from them, just had to be inherently "inaccurate".
Those were the days before the .22 and 6mm PPC were developed on the x39mm case.
The later editions of "Small Arms of the World" that were edited by Ezell, are far clearer and more objective. The Ezells avoid the contradictions that inevitably follow from the Smiths' apparent use of similar criteria for truth and validity to those famously elaborated in the pronouncements of both the late united state Supreme Court Justice Oliver Wendell Holmes, and of soviet Comissar Lysenko.
Back to x54.5mm Swiss based wildcats. Happy experimenting!
Broom, ICL &MM you all make very good points of this being a somewhat redundant project. The head diameter being what it is, and not fitting any current U.S. bolt face diameter, will forever limit all the good Euro cases from ever being chambered in the U.S.. The reason the case appeals so much to me is that: you could move the shoulder to any position on the body, so theres no more than one bullet diameter neck length, which would add some capacity depending on bullet diameter. If the neck length was left as is, it would be perfect for 9.3 caliber and no case capacity would be lost. if you pushed the shoulder forward until you had a neck length of 257" then capacity would surely be added to the case, which would likely rival the 25-06 but in a much more substabtial case. Any caliber in between .284 and .323, you would also see slight added capacity by pushing the shoulder forward to make the neck length match the bullet diameter. Yes the 6.5-284 is a phenominal round, I had one . The SR case with the shoulder moved forward to give you a neck length of .264" would give you enough added capacity to probably outperform the 6.5-284. Plus depending on desired neck length it could give you a longer neck allowing for seating depth versatility and MIGHT be easier on throats(?). One has to wonder why the Euro engineers make their cases with the larger head diameters across the board. Does the larger diameter spread pressure over a larger bolt face surface area, reducing pressure on the total designed lock up system of the action ? Does a larger head diameter give better bullet to bore alignment enhancing accuracy? I personally don't like the 284 case, I've had 25-284, 6.5-284, 284win, and had problems with them all feeding. Most of the trouble was the rebated rim ducking under the bolt head and tipping the back of the cartridge down into the mag well. Another problem is seating bullets, the short neck doesn't give you much to work with without impinging on powder space and is hard on throats. I'm thinking if you were to use say a standard length Rem. action, and use a window box magazine or single stack mag, that any problems with the fatter SR case could be negated without having to work on the feed rails, therefore ruining the action for any other cartridge. Other than opening the bolt face to a other than U.S. diameter, (which could be reversed with a shim in some actions) I don't see alot of other alterations needed. I'm aware of the downfall of the Dakota line being caused mainly by the odd size bolt face, many refuse to look at anything out of the "norm". It's this closed mindedness that keeps alot of really good Euro cartridge platforms out of the U.S. market. I didn't care about the Dakota size case head when I designed my 8mm wildcat, it performs flawlessly. If you're going to go through the trouble of building a "one off" wildcat then prepping the action and bolt are just part of it, it's an expected step and expendature. Now, I'm not trying to change the U.S. market, and I'm not saying we should throw out all the great U.S. cartridges because they're junk, I'm just thinking of all the great Euro cartridges that MM references all the time, that will never be seen here in the U.S.. My son will never even know they're available if I don't show him, all he'll know is the 223, 308, 270, 30-06 because that's all that will ever be on our U.S. gunracks.
Hello guys, I wanted to put this in my above post because it's relative to my ideas, of making the SR case a versatile multi-caliber platform, but time didn't allow right then. Ok so I need some help here from someone that's really knowledgable about P.O. Ackleys works. Theres something that has always stuck in my mind about something I read, in either Handloader or Rifle Shooter magazine. They were working with a 280 AI. and in the write up it said. that Ackley found by changing the angle of the shoulder to 40 degrees, it actually lessens the amount of bolt thrust upon firing. Has anyone else read that in any of Ackleys writings ? I've always thought that impossible or they possibly misquoted Ackley. If you're adding combustion space and filling it with powder, then wouldn't the result be increased thrust pressure on the bolt ? I do understand how the powder burns in a case, and that it's actually lofted forward by the primer blast first thus hitting the shoulder. It's this lofting of pwoder against a nearly flat surface they said contributes to the lower bolt thrust (again according to Ackley's writings). i referenced making the SR case into an Ackley platform just to show there could be a useful gain in capacity, if one were to give it the full on Ackley facelift. I only like to improve a case if it's notorious for stretching excessively. I hate uniforming 100brass only to get 3-4 shots out of them so improving makes sense at that point. I don't think the SR case needs any shoulder angle change, being a somewhat fatter case the 30 degree angle probably allows it to feed fairly smoothly. Changing the location of the shoulder is what I'm interested in DEPENDING on caliber. Hopefully when MM gets to Colorado that he will find a piece of SR brass so I can look at it and do some capacity measurements. Knowing capacity would allow me to compare it to other pieces of brass I have on hand, in the 30-06 and 308win families. If I can do that, then I'll post what I find, and WE as a group can decide if it's worth pursueing, and decide what caliber would see the most benefit. I want all sorts of input, optimal barrel length, action type, bullet type & design, optimal powder selection for capacity and bore size etc. The more input I have could limit cost and time if it turns out to be a viable project. Thanks to all who have already gave good solid technical facts, this is what I'm looking for, and it's all knowledge gained on my part, and possibly a benefit to others thinking about wildcatting a cartridge in the future.
EH, the search for a loose, floating about case is already underway in my absence - had the requirement been known three weeks ago before the packing in started you already would have had..
It is too late at night to think too deeply about your and ICL's inputs so maybe overnight the subconscious mind will do that.
In the mean time: why would NEW backthrust come into significant play? A case with more parallel sidewalls has better brake shoes too.
It is too late at night to think too deeply about your and ICL's inputs so maybe overnight the subconscious mind will do that.
In the mean time: why would NEW backthrust come into significant play? A case with more parallel sidewalls has better brake shoes too.
MM that's the question I've been pondering since I read it in a magazine. I just wanted someone who is well read on Ackleys writings to verify if that was indeed in his writings or not. Just like the internet, I don't believe everything I read in the gun rags. Now had it shown an actual quote from Ackley's books then I may think differently. I guess I don't see how adding more powder therefore more pressure, can result in less backthrust, unless the more square case grabs the chamber walls better and decreases backthrust. Is that what you are saying MM ? I can see that, and understand why it would work that way. More surface area and less case taper being able to grab the chamber walls.
MM sorry for sending you on a hunt for stray brass on such short notice, I didn't think I would find anyone with some SR brass. When I was deciding to make a post about the SR, I did figure you would be the one to have experience with the cartridge and would likely be the first to answer my post. Maybe a dumb question but do you also have a piece of 7.5x54mm French MAS ? That would be a bonus if you did...hahaha !
Elkhamr I do not have that but I know where to enquire. For some or other reason the French connection has been to the side of the German and Brit and Swiss and Swedish and Czech in my use and experience and interest. I am almost embarrassed to say that, being of almost unadulterated French blood - and France being where free thinking in rifle and ammunition was the start of many modern established applications.
The unconstrained mind I unashamedly shall always promote and the sons indeed seem to carry it I see. Often that trait of the human faculty is hated by boxed-in opponents to change - or even to merely learn of new knowledge that exists outside of the gun religion and its dogmatic no-go boundaries. Fact simply is that Europe, and specifically the Germanic and paleo-germanic minds have had rifles and cartridges in such perfect marriage of thermo dynamics and metallurgy and combustion chamber physics for so long, and so unknown here that even mentioning them elicits a chorus of "that is un-American!"indignation. There seems to be a thought afloat that science and mathematics never existed outside of the belted-case-and/or-short-neck-era USA, and certainly 130 years ago whatever was done in Germany, France, England and Switzerland, etc. was random stumbling onto lucky breaks and not by pure scientific thinking.
Fortunately there also are the free thinking wildcatters in particularly the USA. Like you already do, they just need to think a little more out of the box and look at Europe for cartridges that already exist and take it from there. Particularly to consider and understand the value of the long neck relative to what the bullet needs to do from the moment of ignition to leaving the muzzle in the most linear and concentric application of every principle of thermo dynamic output.
While I certainly am not overly concerned about back thrust as a function of inter alia braking effectiveness by the case walls my own interest is more focused on bullet behaviour from the muzzle and into the animal than internal and intermediate ballistics. My son is the design physicist and structural engineer and I test my mere understanding of these latter principles with him and therefore I can not speak with authority on case design. My backwards thinking regarding my bushbuck rifle shows that - having started with exactly what I want to happen at the 50 yards target of THAT particular construction - and thinking backwards until I reached the combustion chamber, but then I did not know how to design that, and that was what the forum did for me.
For some or other reason the French connection has been to the side of the German and Brit and Swiss and Swedish and Czech in my use and experience and interest. I am almost embarrassed to say that, being of almost unadulterated French blood - and France being where free thinking in rifle and ammunition was the start of many modern established applications. The unconstrained mind I unashamedly shall always promote and the sons indeed seem to carry it I see. Often that trait of the human faculty is hated by boxed-in opponents to change - or even to merely learn of new knowledge that exists outside of the gun religion and its dogmatic no-go boundaries. Fact simply is that Europe, and specifically the Germanic and paleo-germanic minds have had rifles and cartridges in such perfect marriage of thermo dynamics and metallurgy and combustion chamber physics for so long, and so unknown here that even mentioning them elicits a chorus of "that is un-American!"indignation. There seems to be a thought afloat that science and mathematics never existed outside of the belted-case-and/or-short-neck-era USA, and certainly 130 years ago whatever was done in Germany, France, England and Switzerland, etc. was random stumbling onto lucky breaks and not by pure scientific thinking.
Fortunately there also are the free thinking wildcatters in particularly the USA. Like you already do, they just need to think a little more out of the box and look at Europe for cartridges that already exist and take it from there. Particularly to consider and understand the value of the long neck relative to what the bullet needs to do from the moment of ignition to leaving the muzzle in the most linear and concentric application of every principle of thermo dynamic output.
While I certainly am not overly concerned about back thrust as a function of inter alia braking effectiveness by the case walls my own interest is more focused on bullet behaviour from the muzzle and into the animal than internal and intermediate ballistics. My son is the design physicist and structural engineer and I test my mere understanding of these latter principles with him and therefore I can not speak with authority on case design. My backwards thinking regarding my bushbuck rifle shows that - having started with exactly what I want to happen at the 50 yards target of THAT particular construction - and thinking backwards until I reached the combustion chamber, but then I did not know how to design that, and that was what the forum did for me.
Straighter case walls grip the chamber better, resulting in less back-thrust against the breech. A riflesmith who frequents this forum under the name ASSASSIN, tested this concept by contriving a way to fire cartridges in TC Contender barrels, without the action being attached to the barrel. By remotely triggering a mechanism that initiated the firing sequence, normal 30/30 rounds were found to violently exit a barrel so-chambered, but when a barrel chambered for 30/30 AI was rigged for the same experiment, the case held to the walls of the chamber and did not exit forcefully. They did fall from the chamber after the firing sequence was complete.
I have no idea what paleo-Germanic minds or dogmatic gun religion have to do with this discussion; there are essentially no actions made that are well-suited to the odd head size of the 7.5x55 Schmidt Rubin cartridge. Turn the rim and deepen the extractor groove; you've got a 284 Winchester case.
There is no need for flowery prose. When it comes to making new wildcats, practicality has little place in the discussion. On the scale of wants and needs, this endeavor falls most decidedly on the former side of the beam. If the OP wants to make some wildcat cartridges from the SR case, I think that would be pretty cool. Having worked with more than a few wildcats, I know that in the end external ballistics and terminal ballistics will be wholly unimpressed by what cylinder of brass filled the chamber, or what powder filled that cylinder. Once the projectile exits the muzzle, those details are entirely immaterial. That is the great "let-down" of wildcatting.
I have no idea what paleo-Germanic minds or dogmatic gun religion have to do with this discussion; there are essentially no actions made that are well-suited to the odd head size of the 7.5x55 Schmidt Rubin cartridge. Turn the rim and deepen the extractor groove; you've got a 284 Winchester case.
There is no need for flowery prose. When it comes to making new wildcats, practicality has little place in the discussion. On the scale of wants and needs, this endeavor falls most decidedly on the former side of the beam. If the OP wants to make some wildcat cartridges from the SR case, I think that would be pretty cool. Having worked with more than a few wildcats, I know that in the end external ballistics and terminal ballistics will be wholly unimpressed by what cylinder of brass filled the chamber, or what powder filled that cylinder. Once the projectile exits the muzzle, those details are entirely immaterial. That is the great "let-down" of wildcatting.
MM this is all too uncanny, I too am French, my last name is Puyear pronounced Pu-yare'. No wonder we love the Euro cartridges and think somewhat along the same lines. I also would consider myself a free thinker, and hate my mind being constrained by what I'm forced to use, when I believe theres better out there. Not just talking rifles here either ! When I was presented with the situation to hunt deer, within and around the housing developement, I kinda had to think in reverse too. I can't have bullets blowing through the deer and off into God knows where, and that was my first vision, I knew it was going to have to break the deer down right on the spot, so it wouldn't be jumping fences any dying in someones front yard that hates hunting. I shot a deer there about 8yrs ago with 270WSM when there weren't as many houses, and every darn light in the little drainage came on, and I had to skin out of there and come back when everyone went to work. That's why the guy wants this to be as low key as pissible. So low and slow will be my approach this year...lol. I've never tried underloading a cartridge to see how slow I can get it, and still have safe combustion without detonation, the forum members will likely have the answer as to which powder/primer combination to use in whichever cartridge will get the job done. My shots will have to be 40yds or less, so that all the dirty work is hidden by the large thick willow bank bordering his property. I'm hoping it will absorb some of the sound too. If the neighbors weren't a problem, I would just use my bow, but then I would surely have critters dying right next to houses and in the roads...lol.
Broom it's funny you mention Assassin, I'm currently working on something with him. I haven't picked his brain on the Ackley avenue as far as pressure and bolt thrust. The cartridge him and I are working with is the 250Sav. AI.. I totally agree with everyone that has said it doesn't matter how that bullet gets out of the barrel, and what case was used. I'm more into the learning part of the whole experience. I've already done 2 successful wildcats, and thoroughly enjoyed the work put into it, and now have the knowledge about how brass works. Watching my son and I shoot elk and deer with something that came from my mind and hands is all the satisfaction or validation I need. I could spend my money on a whole lot more worthless endeavors, but I got bit by the wildcat bug years ago, and enjoy it to this day.
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