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Discussion Starter #1
Hello,

I am a beginner and had a question I am hoping some of the more experienced members could answer for me. I am working on a 35 cal wildcat for Indiana deer hunting. My idea was to cut the end off a .358 Winchester die (that I had on hand) and cut and resize .30-06 brass (that I had on hand) to make a cartridge with the required 1.62 case length. Then I thought I would use a standard .358 Win reamer and short chamber a barrel to match the shortened case length. To try and avoid trouble with differences in case base diameter and chamber diameter and to increase case capacity I shortened the neck to .250. I cut the 30-06 brass to 1.63 in and ran it through my die and they seemed to form perfectly well. My main question is how much of a problem it is for my case neck to be shorter than that of the standard .358 Win reamer/chamber? I will be seating the bullets out long so there shouldn't be a big difference in bullet jump. Is the resulting gap "freebore" or is my understanding of freebore incorrect? And how could this potentially affect the accuracy and performance?
I'm trying to use junk I have on hand and keep it cheap as I'm just trying to learn the ropes..
Thanks for your help,
Mark
 

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Mark,

Welcome to ShootersForum! Rules are simple, be nice and join in. :)

I also live in Indiana and have spent a fair amount of time/effort investigating the potential wildcat combinations, while staying within the 1.625" maximum length and .357" minimum diameter. The round I settled on is a wildcat by Gary Reeder, called the 358GNR. It's a 445 Super Mag case (1.620") necked down to 35 caliber. It has a very short neck that is approximately .250" in length. This was a concern for me, initially, but it has become apparently that ignition is reliable (chronograph shows reasonable standard deviation) and the accuracy has been quite good. Your wildcat should be quite a bit more powerful, by the sounds of it.

"Freebore" is the term used to describe the distance between where a firearm's chamber ends and the actual rifling begins. Depending on how much you set back the barrel, you will be reducing, or entirely eliminating, the throat on your barrel. While this is not unheard of, I wouldn't necessarily recommend it for a wildcat where you are already working in somewhat of a gray area where pressures are concerned. A sensible throat will help with accuracy and allow your bullet to exit the case before being fully into the rifling.

Do you have an action in mind for this project? As mine is a rimmed cartridge, I went with the single-shot H&R action. Here are a few pics of the cartridge and some of the early groups I shot with it. http://picasaweb.google.com/jason.broom/358GNR#5434148387087786418
 

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Discussion Starter #3
Broom_JM
Thanks for responding. I've actually followed some of your threads regarding these cartridges before deciding to try this on my own. I thought long and hard about the 358gnr also and I think mine will be about the same velocity. Seems there are several middle of the road offerings like this (357 Herrett Short, 358 Gremlin, 35/30 BR etc.) My brother will be using the 35 wssm and its an awesome round but I like the idea of a 180 grain bullet in the 2400 fps range and not spending 2000 bucks to get a gun. What kind of velocity are you getting with the 358 GNR? Any idea on case capacity in grs of water? My formed cases hold almost 42 grains of H2O when filled to the case mouth. I think I could get 33 or 34 grains of Lil' Gun to case neck. Have really no idea what kind of velocity to expect but hoping for 2300 to 2400. We'll see.
In regards to my question, I will be chambering a new barrel, just stopping the reamer short of full depth, and so will not be setting it back so the throat will be normal 358 Win throat. But thats my concern....my case neck is only .250 and the .358 win neck is .36. What effect could this have on my accuracy? I would like to use a standard reamer to chamber this.

I guess I could use a 243 reamer and a 35 throater...?
Mark
 

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Mark,

I'm getting just over 2,000fps from the 200gr FTX, but the accuracy is very inconsistent. Sometimes it shoots OK groups, but I really think the rate of twist in this particular barrel (reamed out .357Mag barrel) is probably too slow at 1:16, or maybe 1:14. I haven't slugged it to find out. The 180gr Hornady SSP gives much better accuracy and it's coming out around 2,250fps. I haven't pushed either loading yet, as I really want to give a different powder a try. According to QL, and a couple of guys with a lot more experience than me, Ramshot X-terminator might be capable of better velocity, so I want to pick up a pound of that to see what it can do.

I have measured several of the 358GNR cases and they held a very uniform 45gr of H2O. I'm a little surprised that yours hold less. I'm at a loss to explain that, since yours has an equally short neck. Much thicker brass in the head of your case?

I wouldn't be all that concerned about bullet jump from case mouth to the throat in your barrel, but you ARE planning to turn or ream the necks on those cut off '06 cases, aren't you? I would be concerned when employing a standard reamer the way you have described it, that the diameter of the chamber might demand that you thin the case mouth significantly, so that it can expand to release the bullet when fired. There are tons of little things to consider, but that's half the fun. :)

If you're using '06 cases, why would you use a .243 reamer? Forgive my ignorance, but with the much faster body taper of the '06 case, I'm not seeing how that would work. Because you're cutting it shorter? I'm a little :confused: here.

The latest wildcat I've become very intrigued by is the idea of a 450 Bushmaster, necked down to 35 caliber. This would need to be on a bolt-action or AR-10 platform, because the 450BM round (and the parent 284 Win.) has a rebated rim, which makes it less-than-ideal for a single-shot or lever-action gun. A Remington R25 could be used, or any bolt-action with a .473" bolt face.

The 450BM is a straight-walled case that measures 1.700" long. Necked down, it would need very little trimming to be Indiana-legal. Although it is held down to 38,400psi in the AR-15 rifles that it is mostly chambered in, the case itself is capable of ~55,000psi. (Both the parent case and its first off-spring, the 30RAR run that hot.)

If you were interested in getting the most possible performance from a lever-action rifle, one could take the 338 Marlin Express and neck it up to .358 (with a slight trim) to get velocity somewhere between a 35 Remington and 358 Winchester. Either of the two options above would give a bona fide wildcat capable of cleanly harvesting a whitetail out to 225-250 yards.

Keep us appraised of how your efforts turn out.

Jason
 

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Discussion Starter #5
Jason,
The idea to use a .243 reamer was suggested to me by a gunsmith friend who uses a 243 reamer and 35 throater to chamber for 358 Winchester. I am using 30-06 brass but am cutting them short and forming them in a shortened 358 Win die so the dimensions of the case match the dimensions of the forward 1.62 inches of the 358 Win/243 Win. The measured dimensions seem to match ok. We'll see if it works.
I am also surprised that your 358 GNR has greater case capacity, but then you should also have the 358 Gremlin beat by a solid margin? and they're reporting 2325 fps from a 17 in barrel with Lil'gun powder/180 grSSP's so I would think you could do much better. Here are some case capcities I have found online:
357 Max - 34 gr H2O to mouth
357 Herrett - 40.8 gr H2O to mouth
357/44 Bain Davis - 35 gr to mouth
358 Gremlin - ?
35-30 - 47.4 gr H2O
.445 supermag - 47.6 gr H2O- The difference must be in web thickness, do you know of a better case for me to form from?
I measured case capacity prior to fire forming so maybe I'm off a bit, either way they're close enough that I'll be very interested in what powder works for you. The 450 BM idea would also be cool especially if a guy wanted to use an old Mauser action and standard bolt. (thats why I started thinking about the 308 family of cases, had an old Turk mauser) It would be about as close to the 35WSSM as you could get with a standard bolt face.
Yes I am going to be turning case necks.
Let me know what powder works for you.
Thanks
Mark
 

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Mark,

Thus far, I have found that 4227 is a little too fast, as are H110/W296. The old W680 would have likely been perfect and that was the powder of choice when the 445SM first came on the scene. The groups shown in the picture were obtained with IMR-4198 and I would not hesitate to use that very load to hunt with, if I don't find something a little faster that still retains good accuracy. As I said, I really hope to try some Ramshot X-terminator; it looks very good, according to QL.

My interest in the 450BM, as a parent case, is that you would have little trimming to do, most likely no reaming (depending on the chamber cut) and unlike the WSSM actions, you would be free to seat your bullets long. You could even have a pretty short neck, since the magazine on any rifle chambered for the 284Win, 6.5x284 or 450BM is going to be plenty long enough to give you wiggle room.
 

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The .357 AutoMag cartridge has a .250" neck and 20 degree shoulder with a body diameter of .461" at the shoulder. You might be able to do something with that reamer/sizer.
 

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One very good & interesting thread, Mark & Jason! I was looking at one of my editions of Cartridges Of The World by Frank C. Barnes. In the wildcat section of his book he lists a shorten version of his .458 X 2" American which is a .458 X 1.5" Barnes. Just wondering this cartridge, which would have more powder capacity than a shorten .30-06 case, necking it down to calibers like a .44, .41, or even a .35 caliber might be prudent? The length would be right for Indiana use being 1.5". Just a thought I had.
 

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One very good & interesting thread, Mark & Jason! I was looking at one of my editions of Cartridges Of The World by Frank C. Barnes. In the wildcat section of his book he lists a shorten version of his .458 X 2" American which is a .458 X 1.5" Barnes. Just wondering this cartridge, which would have more powder capacity than a shorten .30-06 case, necking it down to calibers like a .44, .41, or even a .35 caliber might be prudent? The length would be right for Indiana use being 1.5". Just a thought I had.
Davers,

I saw where a lot of wildcats had been built on a 308x 1.5" case (by the author you mentioned, Frank Barnes) but I didn't know about a .458 x 1.5" case. Is that the 458 Win Mag? I noticed a wildcat that Gary Reeder made by cutting a 45/70 case, blowing it out straight, THEN necking it down, but that just seems like too much work! :)

I'll dig out my copy of COTW and look for that 458x1.5...thanks for the heads up!
 

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Davers,

I saw where a lot of wildcats had been built on a 308x 1.5" case (by the author you mentioned, Frank Barnes) but I didn't know about a .458 x 1.5" case. Is that the 458 Win Mag? I noticed a wildcat that Gary Reeder made by cutting a 45/70 case, blowing it out straight, THEN necking it down, but that just seems like too much work! :)

I'll dig out my copy of COTW and look for that 458x1.5...thanks for the heads up!
Yep! I believe Frank Barnes developed it as an experimental "Sub sonic" load for the miliitary. It is made by trimming the .458 Mag. to 1.5". Other magnum cases can be used too like the .300 or 7 m/m Mags. to form the .458X 1.5" Barnes cartridge. I think it would be easier to form the case to 2" and then neck it down then shoorten to 1.5 or 1.6" to form your wildcat cartridge. a wildcat cartridge of around .41 cal. (.410") would be a good one.:)
 

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Isn't the 450 Marlin just a standard-length magnum case, cut to a straight-walled 2.1"? I could maybe start by necking that down to 41, then trimming to 1.625". It would be like a 41 Super-Duper Mag. :) Or, it would be a big financial cost for a minimal gain...which pretty much describes all but the very best wildcat rounds. What can I say? I'm a glutton for punishment! :D
 

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Isn't the 450 Marlin just a standard-length magnum case, cut to a straight-walled 2.1"? I could maybe start by necking that down to 41, then trimming to 1.625". It would be like a 41 Super-Duper Mag. :) Or, it would be a big financial cost for a minimal gain...which pretty much describes all but the very best wildcat rounds. What can I say? I'm a glutton for punishment! :D
You would be right inthat it (the .458X1.5") necked down would most likely just duplicate some other wildcat cartridge, with the same ballistics. The .450 Marlin is like the .458X2" AMERICAN other than the .450 Marlin has a wider belt.
 
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