Here is the "rogue's gallery" of .375 caliber wildcats I have been toying with.
 

 
On the left is the .376 Steyr, not a wildcat, but the one "that started it all" for my interest in the .375 caliber.
 
To its right is the .375/.348 Win. An excellent cartridge with respect to ballistics, and one I am seriously considering for the double rifle/cape gun project.
 
To its right is the .375x56R cartridge. The parent case being the 8x56R found in the M-95 Steyr military rifle. The reason I'm interested in this cartridge is that I am in the process of modifying a bunch of 91/30 Mosin Nagants I bought for $10 each. This cartridge would require only modification of the feed rails and magazine to work in that action. So converted, they would make excellen "Alaskan" rifles.
 
To its right is the .375x55 Swiss and .375/.284 Win cartridges. They are essentially identical, with the only difference being rim diameter. The x55 has a nominal rim diameter of 0.500" and the .284's nominal diameter is .473". Outstanding cases both of them. One of my K-31s is going to become a .375.
 
Finally is the .375-08. I include it here only because I had a cartridge made up for the ".308 Family" picture. I think the weight of the .375 bullet is just a little big too much for the .308 Wincheaster case, but I could easily be talked out of that position.
 
Paul

The .284 rim is WHAT?

Paul, I think I would like the 375/308 best. I have no need for one but with this short case, it looks like it would be a good short range thumper in most any action including short action bolt guns. I think I would like it better than in 35 caliber. What kind of velocity can one expect from this cartridge using 270 gr. bullets in a 20 inch barrel?? ............Paul

Typo Don... should be .473" not .373". I'll correct it.
 
I'll "run some numbers" through QL and see what it says Paul, but it seems that I couldn't get it to 2000 ft-lbs at 300 yds, but I could with the .358. I'll post the numbers later.
 
I tell ya... I really like that .348 Win case for a double or a cape gun.
 
Paul

Something like a short mag 375 would be neat, a .375 WSM or .375 RCM.
 
.358 Win looks like pretty decent performance, not sure if enough case capacity for a 375 caliber. Guess you could run 225gr Hornady, 235gr Speer, or 260gr Partitions.
 
Can you modify the neck on the x54R like the last three? Would give you more case capacity for sure.
 
Hard to compete with .375H&H, .375 Ruger, 378 Weatherby in shoulder busters.
 
Lee book has dimensions/load data on a lot of cartridges. May help.

QuoteCan you modify the neck on the x54R like the last three? Would give you more case capacity for sure.

Essentially that's what the third case from the left is - .375x56R.
 

QuoteHard to compete with .375H&H, .375 Ruger, 378 Weatherby in shoulder busters.

The .376 Steyr has every bit of the performance of the .375 Ruger.

Paul

I just ran across this thread while researching the possibilities for the 375-08. I'm a big fan of the 358 Win, and I'm not much of a shot at distance, so I would love a solid thumping caliber like this. Has anyone successfully pushed the 308 any larger than 375?

Great stuff, Paul as usual. I would like to see the granddaddy of them all....the good old 375H&H stacked up with them. But of course, that takes all the fun out of tinkering!:D Also where is the 375 Whelen Inproved? Regards, Rick.

QuoteHas anyone successfully pushed the 308 any larger than 375?

I'm almost certain there is a .40 caliber bullet on a .308 Win case, but it is for all intents and purposes, a straight-walled 2" case. The "shoulders" are more like snake hips.
 
Rick - The .375 H&H and the .375 Whelen aren't in the picture because they're not among those .375 cartridges I am 'playing' with. I can make a picture including them though.
 
By the by... Turns out that I used the .416x.348 Win instead of the .375x.348 Win, in the Cape gun I made. MAN! I like the .416x.358 Win!
 
Paul

That's what I kind of figured.  I would love to put together something in that category for a short to medium short brush gun for a bolt gun.  I guess it's just not practical.  An option would be to use the WSM case and load at low pressures with heavy cast and/or pistol bullets.  It's just dreaming at this point until I get some other projects done, anyway.  Paul, would it be possible to show that picture of the 375-08 so I can see it?  Remember my limitations re: picture attachments.  My server won't open the pictures above.

Steve,
 
Here 'tis. '08 on right.
 
Paul

Hey Paul do you think the 375x56R would work on a Lee No1. Mk1 action as I would like to build a Lee Speed look alike rifle with that particular chambering.

Something like this.
[ATTACH]14025[/ATTACH]


Do you have a reamer for that wildcat?

And yes I do like attractive tomato stakes just in case anyone is asking.

Cheers

Jorge

I'll check, Jorge.

I do not have that reamer, BUT... I do have a .416x348 reamer. :D

Paul

Quote from: gitano;140297I'll check, Jorge.

I do not have that reamer, BUT... I do have a .416x348 reamer. :D

Paul

Thanks Paul.

416/348 Win sounds interesting but not sure how it would feed out of a SMLE mag. Would need to get a Gibbs 45-70 SMLE mag maybe.

Cheers

Jorge

Jorge - The 8x56R rim is nominally 0.556". The .303 British's rim is nominally 0.540". The rim on the 7.62x54R Nagant is nominally 0.570". Regardless of the small differences in the the rim diameters, these three cases tend to "work" WITHOUT MODIFICATION in any of the other two action's BOLTS. That's NOT to say they "work" from the other two's magazines.

When I was toying with converting some Nagants into .338 caliber it was necessary to enlarge the neck area of the magazine to accommodate the larger .368" diameter neck. Not a 'big' deal, but could not be over-looked. The point being: Feeding from a magazine IS A BIG DEAL. Small changes make big differences. "Differences" meaning "no workee". I think there would be no problem using the .375/56R cartridge with a SMLE bolt, BUT I feel quite confident that one would need to 'adjust' the magazine as necessary to get proper feeding.

The .416/.348 'suggestion' was mostly a joke. :) BUT... the .416 is a great caliber in my opinion, and the resulting x56R cartridge has all the "kick" (at both ends), necessary for just about everything on the planet. The choice of bullets for the .375 is significantly better than that for the .416, and .375 will also handle everything on the planet.

Paul