RE: 38/55 caliber?
I may get some of my facts a bit twisted but one thing I discovered quickly. Factory ammo shot so much better than my handloads. Factory ammo was miked at .381 while most dies for cast bullets sized at .379. The difference of 3 thousands was enough to destroy accuracy in the older and much used Winchesters of the time. However, the one box of factory ammo that I had was a real paper puncher and my subsequent smaller diameter cast bullets in handloads gave a dismal performance. Also, the 55 represented grains of black powder, not smokeless.