.38-55 was the first caliber that the Winchester 94 came out in. They were still having problems with pressure in the .30-30, so the first .30-30's came out in late 1895. You might need to change out the cartridge lifter. Factory .38-55 is like an overgrown .22 Magnum, but loaded to 1800 f/s, it is a totally different animal. I have used .375 Winchester cases in a pinch, but only for lead loads. The pressure levels of .375 are too high for a standard 94 action. The .38-55 started life as a target round, so you can expect excellent accuracy.