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Discussion Starter #1
So I have always wanted to create my own wildcat round, but have never been able to find anything interesting enough to try until Ohio changed is rules on SWC for deer in 2017. The plan was to build a smaller caliber cartridge that would be able to take advantage of higher BC bullets, still have good velocity and fit in a standard action without a lot of modification.

What I ended up with belted straight wall cartridge in 375 cal. The cartridge is based on a belted case with a .473 rim and 2.494" case length. I am currently making the case out of 30-06 brass. The cartridge fits right into any long action with a .473 bolt face. I am currently using a Remington 783. Pushing a 270 gr Hornady Interlock 2,350 fps.

The end results is a round with less recoil than a 450 bushmaster, much flatter trajectory and 1/3 the wind drift.
 

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That's quite the 1st post, seems to be some discrepancies in the description.
 

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What the fellers meant to say was, Hey 375Carp...Welcome to Shooters Forum! :)

A belted 375 Whelen has got to be a whopper of a cartridge. Is that essentially what you've built?

I remember reading a couple of different comments on the steps required to put a belt on a cartridge, with most concluding that the juice was simply not worth the squeeze. (Pun completely unintentional!)

Are you, in fact, using 240 Weatherby brass as a starting point? You'll find some extremely knowledgeable wildcatters on these pages...some of the most inventive guys in today's gun world.

Again, welcome!
 

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I couldn't understand the op. But I hunt with a 375 and must say for deer the 270 gr Hornady Interlock is NOT a good choice. I killed 6 deer with it, but it shoots clear thru any deer 375 in, 375 out. All my whitetails were heart shot at 75-156 yards.

I have since changed to the 220 grain bullets in 375 made for 375 win. much better performance that the 270 gr. But the 270 grain were more accurate.

Welcome Carp, hope to hear more about your wildcat.
 

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What the fellers meant to say was, Hey 375Carp...Welcome to Shooters Forum! :)

A belted 375 Whelen has got to be a whopper of a cartridge. Is that essentially what you've built?

I remember reading a couple of different comments on the steps required to put a belt on a cartridge, with most concluding that the juice was simply not worth the squeeze. (Pun completely unintentional!)

Are you, in fact, using 240 Weatherby brass as a starting point? You'll find some extremely knowledgeable wildcatters on these pages...some of the most inventive guys in today's gun world.

Again, welcome!
Absolutely welcome to the forum, all too often, unless someone introduces their self as being new, I overlook the number of posts and jump right into the thread.:eek::eek: Hope you post often 375Carp and contribute and get something out of participating.:)
 

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I remember reading a couple of different comments on the steps required to put a belt on a cartridge, with most concluding that the juice was simply not worth the squeeze. (Pun completely unintentional!)
Are you, in fact, using 240 Weatherby brass as a starting point?
The link above to R A Dynamics says you can make 240 Weatherby cases from 30-06 cases by runing them into a 240 sizing die. I don't know if that means a 'belt' will be swaged onto the case, or you would simply be headspacing off of the shoulder like a rimless case. I have a set of 240 dies. Just to see what happens, I think I'll go down stairs and lube up a 25-06 case with some Imperial wax and shove it in the 240 FL die and see what comes out. If interesting, I'll post before and after photos
If it works (meaning forms a 'headspaceable' belt), It sure would be a lot more economical that buying [very costly] 240 Weatherby brass, not to mention even readily finding 240 brass.
 

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I don't want to stray from or 'high jack' 375 Carp's, so I'll open a new thread under the 'Handloading Procedures/practices' heading.
Again, welcome 375Carp, would like to see some photos of your finished case and hear more about the specifics of your parent case and forming procedures, intriguing.:)
 

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Discussion Starter #10
Thank you for all the replies. I have discussed this on a couple of other forums over the last year or 2 and get the standard why would you want to do this. I did start out using a 240 weathby as a parent case. I would increase the body taper sightly using a 220 swift die. Then blow it out by fire forming. The fire forming requires a lot of special steps. in order not to split it. It did not make the best brass, but it worked.

I stumbled upon a die specifically made to form the main body and belt on a 25-06 case. It is made by CH4D. Nice group of guys. I picked it up this week. So just a couple of days ago I picked up some new 30-06 brass and some 250 gr Hornady GMX. The belt forming die works well. It does leave a little rolled brass at the front edge, so it does not look quite as pretty as the factor belt, but head spaces well.

The next step is to us a modified 220 swift body forming die. I reamed out the neck to about .400". This allows me to take the rest of the body down to the proper taper so that the cartridge chambers. Then I fire form. Last a very slight trim and I am done. A belted straight wall 375 out of a 30-06.

I shot these new cases for the first time shooting the 240 gr GMX. Used 2 cases to only for the pressure build up loads to get some loads on a case. 5 rounds on each and no sighs of any issues.

I have not shown any pressure signs so far and have went over 2400 fps.
 

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Discussion Starter #11 (Edited)
HarrySS I agree that the 270 interlock is not the best bullet for deer. It did work well on the deer this year, but lighter bullets designed for the 375 win would have better performance. Unfortunately I have an issue with the light bullets. I have cut the chamber to allow for higher bc bullets without going super deep into the case. This leads to excessive free bore for light flat base bullets. I just tried the Hornady 250 gr GMX today. It may be just what I need.

Overall if I was to do this build over again, I would probably shorten the free bore about .040" to .050". That would give me more flexibility to use some shorter bullets.
 

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It is amazing what you can come up with when read cartridges of the world before you go to bed.
^^^^Funny....and true.

Do you also have a copy of Ken Howell's "Designing and Forming Custom Cartridges"? (As well as a copy of QuickDesign software?)
 

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375Carp
Could you measure a case, above and on the belt, formed with the CH4D forming die? I'd like to compare those dimensions to what I got forming a 25-06 case in a 240 Weatherby FL die. I opened a new thread showing my dimensions and photos. Sounds like the CH4D die is the way to go.:)


P.S. Since you've modified the 220 Swift die for proper neck diameter, it seems starting with factory 35 Whelen cases [as 'parent'] would yield better success rate in taking the neck up to 375, than one of the smaller calibers(?).
 

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Discussion Starter #15 (Edited)
crooked creek, I posted the measurements over on your other thread.

When I started looking at using 30-06 based cases, I wanted to use the 35 whelen. Unfortunately, when I designed the cartridge I planned on using the 240 weatherby case. As such, I know the case neck was going to be a little thin. So when I designed it I planned on case walls in the neck of .0125" or less. They actually come out around .009" or so. I believe 35 whelen has case neck walls of .015". I am afraid that if I used it the case necks would be too thick and could create a high pressure situation. The 30-06 brass that I formed after comes out right at the high side of what I need.

If I know then what I know now I would have designed the cartridge to be .405" at the neck and used the 35 whelen brass. I think this would make the design a little better.
 

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Far be it from me to discourage a fellow wildcatter, I've been at this game a VERY long time and have come up with some REAL DOOZZIES, a LOT of nightmares and STILL coming up with a few now and then.

My question is WHY go to all that trouble to come up with a belted '06 size case when the 240 Weatherby has been around for a long time and just needs fire-forming in a 375/240 W chamber.? I'm guessing this has already been done just NOT scattered all over the web or put in any book...my mantra is K.I.S.S. and that seems to work most of the time.

My other question would be, again, WHY BOTHER with all that work, there are MANY cases that could be used, belted or not. What about the 375 JDJ or the 450 Marlin necked to 375...BOTH are available right now. ..or ANY belted mag case trimmed to whatever length you want and necked to 375 or....

AND, why even bother with a belted or '06 case when the excellent WSM case is available in several calibers INCLUDING 375...or maybe one of the shorter, large cal pistol cases like the 460 or 500 S&W...besides we already have the 375 Super mag, 375 Win and 38-55 x 2.125" that do a pretty good job when loaded to modern rifle pressures.

Don't be discouraged and DON'T stop thinking...being thought of as "out in left field" is the way Einstein worked out his famous theories and so did a LOT of other famous geniuses. "Wrong" thinking isn't necessarily a "wrong" way to think, just like "being politically correct" is just so much mindless "unthinking" from the "unthinking", unwashed masses.

In this game you have to have thick skin and confidence in your abilities, understand you WILL make bone head mistakes thinking along one set of parameters and forgetting who you are, then posting those glaring mistakes and understand that humans are no different than primates...we just HAVE to bite.


Good Hunting and keep thinking.
 

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375, I like the GMX bullets for deep penetration. I like them in my 9.3x62 for BIG browns, I treat them as a solid.

would appreciate if you report on how they work with whitetail.

enjoy sounds like a nice rifle for OHIO.

Harry, hnting on the otherside of the ohio.
 

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Discussion Starter #18
Far be it from me to discourage a fellow wildcatter, I've been at this game a VERY long time and have come up with some REAL DOOZZIES, a LOT of nightmares and STILL coming up with a few now and then.

My question is WHY go to all that trouble to come up with a belted '06 size case when the 240 Weatherby has been around for a long time and just needs fire-forming in a 375/240 W chamber.? I'm guessing this has already been done just NOT scattered all over the web or put in any book...my mantra is K.I.S.S. and that seems to work most of the time.

My other question would be, again, WHY BOTHER with all that work, there are MANY cases that could be used, belted or not. What about the 375 JDJ or the 450 Marlin necked to 375...BOTH are available right now. ..or ANY belted mag case trimmed to whatever length you want and necked to 375 or....

AND, why even bother with a belted or '06 case when the excellent WSM case is available in several calibers INCLUDING 375...or maybe one of the shorter, large cal pistol cases like the 460 or 500 S&W...besides we already have the 375 Super mag, 375 Win and 38-55 x 2.125" that do a pretty good job when loaded to modern rifle pressures.

Don't be discouraged and DON'T stop thinking...being thought of as "out in left field" is the way Einstein worked out his famous theories and so did a LOT of other famous geniuses. "Wrong" thinking isn't necessarily a "wrong" way to think, just like "being politically correct" is just so much mindless "unthinking" from the "unthinking", unwashed masses.

In this game you have to have thick skin and confidence in your abilities, understand you WILL make bone head mistakes thinking along one set of parameters and forgetting who you are, then posting those glaring mistakes and understand that humans are no different than primates...we just HAVE to bite.


Good Hunting and keep thinking.
Well, first off, thanks for the post. In regards to why not blow out the 240 weatherby. I did and had reasonable success. Blowing out the case proved to be difficult though. It tended to want to split annealed or not. So then I started opening it up partially setting it up this sizing ball. That caused the neck to sometimes be uneven and then still split 1 or 2 out of 5. Then I found that if I anneal and only sized the neck up to the venturi shoulder, leaving it at 240 at the venturi and 30 cal at the neck it would work 95% of the time. Would still be uneven at times.

So with that working, I was still dealing with $2.00 brass that gave me a neck thickness that was a little thinner than I liked. It also formed up about .035" shorter than I had planned. Other than that it worked fine and killed a deer this year.

Using 30-06 brass reduces the number of steps to form a case by about 50%, the brass is less than $1.00 each, gives me a better neck thickness and last but not least forms out right at 4.500 which leaves me enough to true up for the correct case length.

As far as why a not one of the many suggestions you mentioned? In Ohio for deer you cannot have a bottle necked cartridge. I know it is stupid, but dems the rules. I wanted a higher bc bullet. I can -push similar velocities with my 45/70 or my 444 (which I don't own yet but will). These rounds will have more recoil and have the bc of a bread truck. So bullet drop is predictable enough, but wind deflection is not. For example, at 300 yards a 450 bushmaster will deflect 23" and my load less than 9 with a 10 mph wind.

So the whole reason, good velocity with a high BC bullet. In order to do that you need a case long enough to hold the long pointy bulled and have the case capacity to hold the powder. It also needs to go into a rifle without $500 in gunsmith work. Dropping into a long action without modification was a must, which it does.

I don't know if I covered all of your points, but feel free to fire back. I won't get mad, but do like to discuss.
 

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broom_JM A belted straight wall 375 whelen is pretty much what I was looking for. Ohio lawmakers do not like shoulders on their cartridges. It is amazing what you can come up with when read cartridges of the world before you go to bed.

Indiana also has some very weird regulations, which is why I have worked with a few oddball cartridges over the last 10 years or so.

I take 303 British cases and turn the heads down to make 35 Remington brass that is a little more sturdy than they would be normally. I got that idea from reading COTW and PO Ackley's 2nd Edition, late at night. ;)
 

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crooked creek, I posted the measurements over on your other thread.

When I started looking at using 30-06 based cases, I wanted to use the 35 whelen. Unfortunately, when I designed the cartridge I planned on using the 240 weatherby case. As such, I know the case neck was going to be a little thin. So when I designed it I planned on case walls in the neck of .0125" or less. They actually come out around .009" or so. I believe 35 whelen has case neck walls of .015". I am afraid that if I used it the case necks would be too thick and could create a high pressure situation. The 30-06 brass that I formed after comes out right at the high side of what I need.

If I know then what I know now I would have designed the cartridge to be .405" at the neck and used the 35 whelen brass. I think this would make the design a little better.
Thanks for responding on my thread, the info gives me 'cause' to play a little more.
I hear what you are saying about neck thickness, but with all the effort you are already going to, can't you simply add another step and turn the necks (or inside ream) of 35 Whelen brass? You would get 'two for the price of one' with that by getting exactly the neck thickness your chamber 'wants' and the thickness would be dead on consistent around the circumference, no? Just a thought.:)
 
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