375 Winchester

Fire Arm






: Marlin 375

: 20 inches

: 1:18 inches

: 24 X

: 50 yards

: 10

Click for detailed 375 Winchester Tech drawing
Click on figure to access ANSI
technical cartridge drawing

A commercial cartridge, maybe an already obsolete cartridge. Introduced by Winchester in 1979 as a new cartridge for the then new Model 94 XTR Big Bore - explicitly introduced as a high performance version of an already existing and venerable cartridge - the 38-55 Winchester; and as an explicit attempt to separate the low pressure 38-55 Trapdoor appropriate loads, from higher pressure loads, entirely unsuitable in a m1873, but entirely suitable for use in a modern firearm. Following the XTR, Marlin introduced the m375, a strengthened m336. Savage and Ruger later introduced chamberings in their respective m99's and #3's. But when, a decade later and with only hundreds of firearms sold, industry support for the cartridge waned. Winchester dropped their chambering in 1987. By 1994 there were no rifle chamberings. In 2002, one factory load was still available, and the Contender could still be had in 375 Winchester.

The 375 was introduced as a woods hunting cartridge, in the tradition of the 35 Remington, but improved; which the cartridge does delivers - the Taylor Knock Down index for stout 35 Rem loads run 21 or 22; the TKD for 375 runs 28 or 29. (In comparison, the 30-30 Win rates a 17, a heavy 38-55 load, 24) A maximum 375 load can generate 2200 fp muzzle energy; well above a maximum of 1400 for the 38-55; and an improvement over 1800 for a 30-30; but well short of heavier hunting cartridges, 3000 fp for the 444 marlin, or 3300 fp for the 358 Win.

The 375 Winchester is the smallest .375" bullet rifle cartridge the industry has ever produced; and therein lies a problem for the 375 shooter, and especially the reloader: bullet selection. Most .375" commercially produced bullets are designed for 375 H&H or 378 Wby use; as such have very heavy jackets to the withstand 4000 fp plus muzzle energies, and to provide deep penetrating bone crushing performance at the terminal end. The 375 Winchester performs best with light bullets, and with thin 30-30 weight jackets (and if fed through a tubular magazine: flat points). As of 2002, each of the major bullet manufacturers offers just/exactly one 375 Winchester specific bullet. Of note, the 375 will shoot any 38-55 lead load, as well as any 38-55, and with a lot less wear to the bore than with a jacketed bullet. 375 H&H bullets shot from a 375 Win can be assumed to behave as non-expanding solids.

The full case capacity of the 375 Win is 47.1 gr (of water); 35.9 gr with a flat base bullet seated at .400". In comparison, the 375 H&H, the nominal .375" hunting cartridge, offers more than twice the capacity of the Winchester, at 90.7gr and 79.5gr, respectively. The 378 Wby, the nominal large 375 cartridge, offers yet another increment over the H&H, 128.1gr and 117.0gr, respectively. Smaller cartridges in comparison are the: 358 Win, 58.8gr and 48.6gr, respectively; 375 JDJ at 64.0gr and 52.8gr; 375 Whelen, 75.1gr and 63.9gr; 444 Marlin, 67.4gr and 52.8gr; 9.3x57mm Mauser, 62.2gr and 51.5gr; or the wildcat, 375 Savage, 51.3gr and 40.2gr. Although the 375 Win case is slightly shorter and the walls thicker, because of greater allowed OAL, it's usable case capacity essentially replicates the 38-55.

As a hunting cartridge it is generally used for deer or black bear out to 150 yards. As point blank range it has been purportedly used on moose and grizzle bear. Although a 375 Winchester round will (unfortunately) chamber in a 38-55 firearm, it must not be discharged there. Nominal bullet diameter is .375". The ANSI maximum pressure is 52k CUP (same as 356 Win, 1k less than the 375H&H and 458 Win Mag). Reloading dies are available from RCBS.

© Copyright Gregory J Mushial 1997-2002