When I saw the first article on this Mossberg Patriot in .375 Ruger, it struck me as a good candidate to play around with.
Back in 1974 I read an article on the .375 Epstein Magnum, a wildcat based on the .375 H&H case (Rifle Magazine #35 - September 1974). It is basically a .338 Winchester Magnum body with a 0.465" long neck for .375" dia. bullets. The case OAL is 2.605" or about 0.025" longer than the Ruger. The Ruger neck is 0.272" shorter than the Epstein. All in all, the Ruger and Epstein are about equal, with the former being a rimless case and the latter a belted case. Being young and entirely stupid, I had to have one.
So I bought an Interarms Mark X magnum action and drove up to RCBS Sportsman Store in Oroville, California. Turned it over to Tom Miller their gunsmith, and ordered it barreled and a set of dies. He used a Shilen CM barrel cut to 26". They also made the forming die set and reloading die set, that cost $77.00 prompting an apology for the expense!
When it came back I sent it up to Grants Pass, Oregon, where the late C.P. Donnelly crafted a stock. He charged $240.00 for the stock. (Loved those 1974 prices)
Loaded a range of cartridges for it, settling on the Hornady 270 grain Spire Point over 79 grains of IMR 4350, which passed over the chronograph at 2,754 fps, developing 4,565 ft lbs of energy. I never tried anything hotter because as it was, recoil slid the stool I sat on back a little every shot. I thought it might make a great elk rifle, but then I never managed to go elk hunting. Now of course I'm too old and patched together to consider such a thing. Still, I have a great rifle, but the .375 Ruger would offer the same performance without forming, trimming, reaming and sizing brass. So at the price of the Mossberg, I'll look for one. If you want a .375 Magnum of one sort or another, don't pass one up. I found the Epstein to be very accurate, often grouping ten shots right at one MOA - and only requiring a couple of Tylenol to quell the concussion headache. May try some .375" cast bullets from Beartooth Bullets in some more sensible loads, why it might even be fun!