Caliber .375 Whelen to Improved or Ackley ?

[missionary5155]

Howdy Bullshop
I can get to your website so a picture here would be redundant.. Thanks !!
I am glad everything worked out. I would not want to have to turn loose of my 86 even being a 33Win. Those 86's are good ones to hang on to.
Mike in Peru

[dakota]

I’ve just built a 375 Whelen AI.

So far have just tried TAC. 55 grains with 270 grain bullet ok.

I’ve worked up from 50 grains.

With only 20-30 rounds fired, I had one case separation. The cases I used are Federal 35 Whelen necked up.

I don’t blame the manufacturer tho.

The case failure was just in front or above the base. It was on the second firing of that case.

Since then I bent a wire and checked for a possible case separation on the other fired cases. I have no such indication. I plan on running all my cases into a 416 expander, then running into my full length sizing die. BTW, the sizing die and the rifle’s chamber are as close to an exact match as I’ve seen.

[dakota]

Just ordered a NOE mold.

[Buckshot]

...........When I built my 375-'06 a lot of new powders have been introduced, but at that time THE powder touted for that cartridge was IMR 4320.

...........Buckshot

[Multigunner]

A lot of reported problems of shoulder set back were most likely due to use of older milspec cartridge cases that did not have the improvements of post WW1 cartridge cases.

Cartridge case geometry was improved to prevent problems found when using Ball ammo in MGs and other slam loaders.
According to Hatcher the WW1 era .30-06 for example could have the shoulder set back by as much as .006" simply by manipulating the bolt of a 1903 very rapidly, and the Marlin aerial guns due to its high rate of fire and lack of buffering when adapted to the straight gas piston from the colt potato digger linkage had to have the chamber shoulders cut short to compensate for excessive shoulder set back.

Stiffer thicker cases with less aggressive annealing solved that problem. Commercial cases may not have followed suit quite as quickly.

[dakota]

Mine is AI. The dies were available as was the reamer. If it were the other way, I would probably been OK with the standard 375 Whelen.
I shot a .82" group with iron sights at 50 meters and aperture sights. I screwed up and deleted the load info.

[dakota]

I decided to put a scope on my 375WAI. The following are the groups/loads were shot with a suppressor:

375W AI M98, 235 grain SPEER, 61 grains H335, 0.73" group with aperture sights at 54 yards = 1.29 MOA (no suppressor)
375W AI M98, 235 grain SPEER, 61 grains H335, 1.97" group with 4x M8 Leupold at 100 yards = 1.88 MOA
375W AI M98, 235 grain SPEER, 61 grains H335, 1.72" group with 4x M8 Leupold at 100 yards = 1.64 MOA
375W AI M98, 270 grain Horn SP RN, 57 grains H4895, 0.82" group with 4x M8 Leupold at 100 yards = 0.78 MOA
375W AI M98, 270 grain Horn SP BT, 57 grains H4895, 0.66" group with 4x M8 Leupold at 100 yards = 0.63 MOA
375W AI M98, 270 grain Horn SP BT, 57 grains H4895, 0.66" group with 4x M8 Leupold at 100 yards = 0.63 MOA (second group - I couldn't measure any difference)

The 57 grains load with 270 grain bullets are maximum - if you have such a rifle chambered for this cartridge, work up carefully. The good news is the above loads hit at close the same POI at 100 yards. The 61 grains H335 with 235 grain SPEER load centered at about 1/2" higher than the 270 grain loads.

235 grain SPEERS traveling at ~2,800 fps, 3" high at 100 yards, -1.5" at 250 yards, -6" at 300 yards.
270 grain Hornady traveling at ~ 2,600 fps, RN 3" high at 100, -3.9" at 250 yards, -11" at 300 yards.
270 grain Hornady traveling at ~ 2,600 fps, SPBT 3" high at 100, -2.3" at 250 yards, -8" at 300 yards.
The 270 grain Hornady SP BT should be good for anything I'll be shooting at. I have a few hundred of the RN 270's - seconds from MidwayUSA - they should be good for most anything I'll shoot at too. More work to be done with the 235.

I have some other 375 bullets on hand. I'm not sure if I'll be getting away from the two bullets tested much though, I am especially pleased with the 270 Horn loads.


This rifle was one I did as much of the work myself, at least what I could do without a lathe. I bought a 98 receiver from a Mauser guru. (I've had Mauser 98's all my life, but I am not an expert on Mausers!) It's a BRNO VZ 24 if that means something to one who would know.
I bought a semi-blank stock - mostly inletted but needing a lot of wood removal. I shaped the stock to fit me and put a Pachmayer recoil pad on it. I bought a blank 375 barrel from Shaw. I rented a reamer and cut the chamber by hand, that is without a lathe. The reamer was available right now and the dies were available right now. I had sold my lathe 30 years ago and while I've opened up chambers by hand, I never started from scratch - uff da - it's a lot of work. (I rust blued the barreled action myself also.)
I hired a gunsmith to mount a decent set of sights, which I had. Steel Lyman aperture rear sight and the front sight from Brownells. I found I could shoot it pretty well at 100 yards, but the first time out deer hunting with it I saw deer at 200 to 250 in the trees. Those sights and my eyes were not compatible with that scenario. I had a Leupold base for a 98 lying around and once again had to rely on a smith to install the base. While at it, the safety was converted to a 3-way safety that works with a scope. I put on a M8 4x Leupold scope, which I consider about right for the cartridge. The barrel is threaded for a suppressor and with that on the rifle, the recoil is mild.
As far as why a "375 Whelen AI", I wanted something different. I've owned center fire rifles since the late 50's and had many different common rifles chambered for common cartridges. I put a lot of work into this rife and it wasn't going to be a 30-06 or whatever some dude thinks it should have been. I figured the 375 Whelen Ai was about the most powerful cartridge based on the 06 case (I was likely wrong as the 400 Whelen might well be a more powerful round.) I also picked 375 because I owned a 375 H&H, a 375 H&H AI, and a 375 Win. I had plenty of molds in 375 and had a good selection of 375 bullets on the shelf. Plus, there is a plentiful supply of bullets on the market. I'm considering a 375-444 Ruger #1 since I have a #1 action that I'd like to modify.
I didn't pick a 35 Whelen AI as I had a 35 Whelen and a 35 Brown Whelen. and felt the 35 Whelen AI was more common than the 375 version.

[lotech]

I haven't had a .375 Whelen Improved in years, but I got excellent accuracy with the 270 Hornady SP and IMR-4064. That was more than thirty years ago. If I had the rifle now, I'd also try H4895. I used several cast bullets in it as well but I'd have to dig out old notes to know which ones.

[Larry Gibson]

Very nicely done, excellent write up.

[W.R.Buchanan]

Did Mike, (Missionary 5155) ever get his rifle sorted out?

That was like 10 years ago. Hope it worked right from JES as I think he knew about teh proper way to chamber the barrels for the .375 and .400 Whelan Calibers