I'm building a 375 Whelen AI. I've got dies and brass. I've shot it a couple of times after chambering to ensure that my fired cases, dies etc were compatible. Good news is the 35 Whelen cases necked up to 416 and then down thru the CH4D dies and the fired cases seem to have worked out fine. I've sent the chambering reamer back. (chambering by hand is a longer process than I remembered) Reamer was rented from 4D reamer rental, A case full of IMR4064 and 270 gr RN blems from Midway seems to be a mild load with rounded primers.
The action is a Mouser - 98 from Checksolvokia (sp?) made between the wars. The barrel is a 2 1/2 contour 22" from ER Shaw. The stock I bought here on 24. I'll put a 1/2" decelerator pad on it. And will hire someone with the proper jigs to attach the Lyman steel aperture site and the front post sight.

I bought "a bunch" of these 270 gr RN bullets a while back when Midway was dumping them.

I've freefloated the barrel and am about to glass bed the action. Still need to put a finish on the barrel led action and the stock.

I've searched the internet and bought a book - "Big bore rifles and cartridges" but am still looking for loads. I have molds and gas checks, Linotype and wheel weights.

If anyone has experience with this cartridge I would appreciate hearing about your experience.

It seems that most shooters use IMR 4064 in this cartridge. I'm thinking maybe TAC, IMR4166 or one of the 4895's might work well.

What would curl my toes would be shooting 235 - 270 grain cast bullets at ~ 2,300 fps. Finally I have a pre-64 375 H&H AI so I don't need > 65,000 psi loads.

H4895 is pretty much the bees knees for reduced loads.

http://www.pyrodex.com/PDF/H4895%20Reduced%20Rifle%20Loads.pdf

You should be able to hit 2300 ft/s at any of those weights at under 45KPSI.

I think I'll be buying "Load data" software too.

I would think .375 Skovill load data would be a good place to start http://www.barnesbullets.com/files/2014/11/375ScovillWeb.pdf since the wildcat is based on the 30.06 case just like your .375 Whelen.

THANKS! The Scvil has a little more capacity, I believe. But I don't think much.
That will help. Thanks again. As I recall the shoulder is moved forward on the Scovil

Bugger - really curious about your build. Would it achieve anything that you couldn't already get from a "standard" design i.e. 9.3X62mm or .400 Whelen at less cost? Yes, I know sometimes the itch just
has to be scratched. Surely, since 1906 (.30/06) or 1912 (.375 H&H) somebody/somewhere had to have tried this combo (maybe Phil Sharpe) and left historical loading data as a starting point. Good luck.
Homesteader

Well, there's not much info on this cartridge, given.

Reading old Handloader and Rifle articles by Al Miller and Dave Scovil tipped the scale for me.

I have this cartridge power covered by others 338 WM, 375 H&H AI, 350 RM, 45-90, 45-70 and others. But I wanted an optimum cast bullet shooter in a light bolt action.

The 9.3x62 is all right I guess, but to get one of those I just would probably buy a CZ. People have already worked up loads and people have already done this and that with it. Arrogant I suppose, but that seemed boring. Would that cartridge be as good as "My Build"? I didn't think so.

I believe it was Al Miller that said 375 caliber was minimum caliber for effective cast bullet shooting of game animals. (I read carefully all that Al ever wrote and I could get my hands on.)

So if not 375, then what? I wanted to use a Mouser as I like the open receiver. Using an 06 case, a 375 Scovill or a 375 Whelen AI seemed to be the best choices. I cut the chamber so that a 35 Whelen case was a good fit. No special fire forming techniques required.

I briefly looked at a 400 Whelen, but bullet availability and shoulder issues stopped that thought.

I considered a 458 WM, a 458 American and others as I am fond of the 45 caliber but I eventually rejected arch for various reasons.

I considered a fat cartridge like shortened ultra magnums and the Ruger cartridges but rejected those too. Mostly they were common and had issues.

So the 'best' boiled down to the 375 Whelen AI. If I get my wife talked into letting me spend the dollars, I'll go to Kodak and hunt with one of my favorite writers or his son Taj to shoot grizzly.