I would like to build a wildcat based on the 308/358 Winchester case, necked up to 375. This case has a bit more capacity (about 10 grains of water) than the 375 Winchester and seems that it would make a really nice big slow bullet thrower for whitetail deer, and would function through a short action as well allowing me to build one on most any action that could be had reasonably cheap.

Can anyone shed some light on what kind of project this would be? There is nothing close to this out there so it seems to me it would be a complete project requiring even the custom making of the dies. Thoughts? Thanks.

This has been done already. CH-4D has the dies, and I'm sure they can tell you which maker offers the matching reamer.



I believe the step up in performance over the .358 would be marginal -- the cross section is only 10% more, after all.

JP,
not to stop a fella and his fun.... yet the 376 steyr is HUGE improvement over this suggest round, and all of .25 or so longer.. and gets near 375 hh ballitics

jeffe

Personally I'd stick with the 358 win, as there are many good bullets for the velocities you'll be able to obtain, and me thinks the 225 gr @ 2400-2500 makes it one of the best all purpose hunting rounds for NA for shots inside 250 yards.

With a 375, you'll be limited to the 235 gr bullets, and the 260 gr partition. The 260 gr partition at 2200 fps would certainly be a good combo for heavy game.

If you just gotta have something more different then do it. The .375/06 I believe was too small of shoulder but the .308 case being a bit broader at the shoulder would probably do good. The 260 grain partition has a more stubby point and therefore shorter for weight in proportion to other partitions which would keep it from crowding powder space.

From experience I can say the .375-06 AI works just fine, no "shoulder problems", though it's not a .375 H&H. As much as I love the .375 bore I would tend to look at the .338-08 with 210gr noslers or 225 gr., or stay with the .358. Just seems to me that the .375 is a little big for the smaller .308 case. Maybe with a larger diameter short action case like the .350 rem mag or wsm's or maybe a steyer or maybe a .375-284?



That said don't let my .02 stand in the way of a fun project and let us know how it comes out.



Eric

I think the 375-08 would be a real fun stomper and not too hard on shoulder in a lighter gun. The 235 Speer would be the perfect white tail/bear/hog/ bullet followed by the 235 X bullet for moose/elk at normal shooting ranges. I chose the 376 Steyr because I ultimately have something bigger in mind to shoot at but were it not for that the 375-08 would have been just dandy for me. BTW, it was the 400 Whelan with the shoulder reputation, not the 375.

I would think the .375-08 might perform rather similarly to the 9.3 x 57 Mauser.

Not a hugely popular round, but it has a repuation as a reliable short-range moose killer here in Sweden. Recoil is not high either.

jpb

you might want to consider a 284 based boomer................
woofer

Guys, Thanks all for your input. This project has been in thought for over a year now and will take another year to put together, but I am very sure of a 375-08 or a 375x57 being the right direction for my wants and needs. I had first thought of a Mauser 57mm case as I was thinking of getting a Yugo mauser for the conversion but thought the 08 case a bit more plentful in this part of the world. Is there a Mauser action that might be better suited than the Yugo? Thanks again, JP

I've seen quite a few folks loading the 35 Whelen 250g to 2500 fps from a 24" bbl, so I'd say at least 2550 fps from the 375 Imp should be doable. Damn fine load, I imagine.

The interesting thing about the 375-308 is that it approaches an expansion ratio where AA 1680 and Lil'gun might work well. My computer says that a 225 gr Hornady can do 2600 fps at safe pressures. That's getting pretty darn useful...

Being a male, I can relate to why you want to do the 375/308, but the 358 is a great round and still different than what most are carrying. Just my .02. Lou

As an interesting side note the myth about the shoulder on the 400 Whelen has been fully investigated. The article at the link below first appeared in Precision Shooting magazine. Unfortunately the myth was caused by the use of incorrect dimensions when trying to recreate the design. Whelen himself tested the 400 Whelen and Elmer Kieth spoke vary highly of it.

Whelen's objection to the case was that it would not lend itself toward commercial manufacture, not that it did not work. This article fully explains the whole thing.

http://www.z-hat.com/smashing_the_headspace_myth.htm