Most .375 Win loads are shot thru rifles with short barrels. Those factory loads I've read chronographed thru the common rifle barrel lengths often don't make it much faster than 1800 fps. At acceptable pressures, the heavyweights in .375 Win are running at the fringe of adequate expansion velocities. A friend who owns one of the very handy, well-balanced Marlins has experienced some poor bullet performance on deer with his rifle. Overall, the .375 Win was not the best-designed cartridge IMO. It could be shot in a .38-55 {not good} and really didn't make the best of what the rifles were capable of handling. Maybe Winchester wanted to be able to make use of .30-30 cartridge tooling and didn't want to make feed modifications to the rifle?

If they wanted a .375, a much better round IMO would have been the .444 case necked down to .375, with a fairly sharp shoulder. Such a round would be similar to the .375 JDJ {w/ shorter OAL for the levergun actions} and, funny enough, would have gotten pretty close in a light carbine to what the .375 2 1/2 does in a rifle.

A Marlin .45-70 could be rebarreled to factory OAL .38-56 or a modern improved version and very good ballistics obtained. In fact, such a round should outdo the .375 2 1/2 and approach .375/06 performance, at least fairly close and would be a real peach for those who like traditional levers.