Anyone know what the barrel on a .38-55 mic's. Don't have the gun here but need to load some ammo for a Cowboy .38-55 made around 2003. The gun has only had 100 rounds of Blackhills .38-55 through it. No help from the guy that shot it as he had no idea. I know the gun may have a different bore diameter but I need a place to start. Do I start with .380 or .375 dia bullets 240 gr RNFP in weight.