The Interesting .375 Winchester
Introduced in 1978 for the Model 94 Big Bore lever action rifle, the .375 Winchester never caught on. Its companion cartridges for the Big Bore 94 were the .307 (a rimmed version of the .308 Winchester) and the .356 (a rimmed version of the .358 Winchester). The .375 Winchester is based on a high pressure version of the .38-55 case, with thicker case walls and a stronger head. Although its case is .065" shorter than the old .38-55 case, .375 Winchester brass can be used for .38-55 reloads if necessary. The reverse is not true, however. Not only is the .38-55 case too long for the .375 chamber, even if trimmed to the correct length the .38-55 case is too thin to safely contain .375 pressures. The .375 is loaded to 52,000 cup, far beyond the safe pressure for .38-55 rifles.
None of the Big Bore 94 cartridges became popular, although the .307 was offered for several years longer than the medium bore pair. The .356 was offered in a version of the Marlin 336 and also, very briefly, the .375 but they failed to achieve any lasting popularity. Savage chambered the Model 99 for both cartridges for a short time. In addition, Ruger built a few single shot No. 3 shot carbines in .375 Winchester, but both the gun and the cartridge are long gone from the Ruger line. The No. 3 falling block carbine allowed the use of a much wider selection of bullets, since it was not restricted by a tubular magazine to flat point bullets--which are scarce in .375 calibre.
It seems that the larger the bore diameter, the quicker the Big Bore 94 cartridge died in the market place. The .375 was the first to go, followed by the .356, and finally by the .307 Ammunition is still available from Winchester for all three cartridges, however. There was a rumour that Winchester had a .400 cartridge (based on the .375 case) for the Big Bore 94 in the works, but cancelled the project after the failure of the .375.
This bit of cartridge history is hard to reconcile with the popularity in Marlin lever action rifles of the .45-70, the successful introduction of the powerful .450 Marlin, and the continued sales of the .444 Marlin. Winchester even chambered the Big Bore 94 for the .444 Marlin; the only cartridge for which that model is now available. And the firearms press has applauded the reintroduction of the .405 Winchester in the Model 1895 rifle. Why have these cartridges been well received and the .375 Winchester such a flop? It is, truly, a mystery to me.
When it was introduced I thought that the .375 would be the most successful of the Big Bore 94 trio of cartridges. I certainly found it the most interesting since it offered good bullet weight, superior sectional density, and less recoil than the .444 Marlin. If I'd had the funds I almost certainly would have invested in a .375 Winchester rifle, but those were lean years for me. By the time my cash flow had improved the .375 was already obsolescent, temporarily saved from extinction only by the T/C single shot hunting pistol. The .375 proved to be an awful lot of cartridge for a pistol, and it has since been dropped from the T/C pistol line. To the best of my knowledge no factory-produced rifle is currently available in .375 Winchester.
Although not commercially successful, the .375 Winchester remains an interesting cartridge. With proper bullets and within its effective range it is suitable for all thin skinned North American big game with the exception of the great bears. (And, personally, I would not feel completely helpless if I encountered a grizzly while carrying a .375 Win. rifle.)
When the .375 was introduced Winchester offered two factory loads. There was a 250 grain bullet (SD=.255) for heavy game and a 200 grain bullet (SD=.203) for deer and black bear.
The 250 grain bullet seemed to me to make the most sense for a .375 bore rifle, but it was discontinued sometime in the middle to late 1990's. The big advantage of this load was the superior sectional density (SD), and hence penetration, of the 250 grain bullet. The muzzle velocity of this load was 1900 fps with 2005 ft. lbs. of muzzle energy. At 100 yards the figures were 1647 fps and 1506 ft. lbs. At 200 yards the velocity was 1424 fps (about like a .38-55 at the muzzle) and the energy 1126 ft. lbs.
The single remaining factory load from Winchester drives a 200 grain Power Point bullet at a muzzle velocity of 2200 fps with 2150 ft. lbs. of energy. The figures for 100 yards are 1841 fps and 1506 ft. lbs. At 200 yards, by which the .375 has pretty well reached its practical range limit, the velocity is 1526 fps and the energy is 1034 ft. lbs. Winchesterís handy game selector lists the 200 grain .375 factory load as a deer and black bear cartridge.
The trajectory of the factory load shows that a bullet from a scoped rifle zeroed at 150 yards will hit +2.1" at 100 yards, 0 at 150 yards, and -5.2" at 200 yards. Given its trajectory and energy figures, I would consider the .375 suitable for deer and black bear out to 200 yards.
The problem with the Winchester .375 factory load for large animals is the relatively meagre .203 SD of its 200 grain bullet. This is comparable to the sectional density of a 265 grain .444 bullet or a 300 grain .45-70 bullet, which are also fine for deer and black bear but a bit light for larger game, and only slightly superior to the SD of a 130 grain .30 calibre varmint bullet.
Reloaders can rectify this situation. Barnes Bullets offers their original style flat point bullets for the .375 in 220 grain (SD=.223, about like a 150 grain .30 bullet) and 255 grain (SD=.259, about like a 170 grain .30 bullet) weights. Hornady developed a 220 grain bullet especially for the .375 Winchester. Sierra has a 200 grain flat point bullet for the .375 that can be used to duplicate the factory load. According to my Rifle Recoil Table a 7.5 pound (with scope and mounts) Big Bore 94 rifle shooting a 220 grain bullet at a MV of 2012 fps should come back at the shooter with 15.1 ft. lbs. of recoil energy.
According to the Barnes Reloading Manual No. 1 their 255 grain Original bullet can be driven to a MV of 1813 fps by 33.0 grains of IMR 3031 powder, and a MV of 1903 fps by 36.0 grains of IMR 3031. This is ballistically much like the discontinued Winchester factory load with the 250 grain bullet. The recoil of this load in a 7.5 pound Big Bore 94 rifle should be about 18.1 ft. lbs.
I hope you can see why I consider the .375 Winchester an interesting cartridge. It can deliver a large diameter bullet of decent sectional density without excessive recoil. Compared to the .444 Marlin and its 240 grain bullet (SD only .185) it is a more efficient cartridge, and less punishing to shoot. But for whatever reason the .375 Winchester has been allowed to become obsolete.
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