.375 Winchester (using Hornady bullets)
Date: Jun 19 2013
The .375 Winchester was announced in 1978 in the strengthened (in the rear quarter of the receiver) Winchester Model 94XTR Big Bore lever action rifle. Ruger soon offered the cartridge in its No. 3, Thompson/Center in the Contender and Marlin in the Model 375 lever gun. Two loads were initially offered; a 200-grain bullet at 2,200 fps, a 250 grain at 1,900 fps.
The .375 Winchester case is shorter than the old .38-55 WCF and much thicker for increased strength. The .375 uses .375-inch bullets, while current Winchester factory loaded bullets for the .38-55 measure .377 inch (not to mention groove diameter varies for this cartridge from .376 to .381 inch). Furthermore, the .375 Winchester operates at 52,000 CUP pressure, while maximum average pressure for the .38-55 is 28,000 CUP, with factory loads being much below that figure. Regardless of rumors, the two cartridges should not be interchanged - doing so may prove unsafe.
The 220-grain Hornady FP bullet was designed to give greater velocities than the 250-grain factory load, but with improved terminal performance over the 200-grain version. The Hornady bullet gave notably greater accuracy in a vintage Winchester Model 94XTR than factory loads. The most accurate powders included IMR-4198, IMR-3031 and Hodgdon H-322, while Accurate 1680 gave the highest velocity.
Cases should be full-length sized, then expanded just enough to accept bullets, then a heavy roll crimp applied. The bullets should be seated so that the case mouth is almost even with the top of its cannelure, then crimped in place.