Senior; I did in fact slug the bore of my New Winchester. The measurement comes in right at .3775" I cannot shoot that Hornady 220 grain in my rifle, although it would seem possible. Every load I tried keyholed at 35 yards or so. The .375" - 255 grain Barnes Jacketed soft point shoots just fine, but not as well as the .377" - 255 grainer designed specifically for the 38-55. Additionally, to get the correct COL with the .375 variety, one must use the shorter 375 Winchester brass, or else the cartridge is too long tho cycle through the 94 action. I am using cast bullets, sized at .379 - .380 with great success in this rifle. I have some in 240, 255, 265 and 285 grain weights. I like H322 and Benchmark, but several powders, including 3031 & RL7 work just fine. Regards, Eagleye.
