I powder coat my cast projectiles and load them according to the cast lead loading data but find some differences in performance which makes me wonder what effect powder coating has on chamber pressures and whether a new set of loading data be developed. I find in my very light pistol loads (32 S&W Long) 1.5 grains I need to crimp harder or add a bit more powder (to up pressure.I think) other wise there is a loss of accuracy , similar with 38 in my revolver but at top end loads I get improved accuracy (9mm) .
Has any one done any testing on various rounds and compared them, for example 45acp fmj compared to 45acp .cast and traditionally lubed and 45acp powder coated. Same with 9mm .38 etc, with the same load of powder and weight bullet.
Does a bottle neck cartridge behave differently and does using them in rifle loads make a difference.
I think a new set of loading data could be required but unless non subjective tests are done it is only guess work. Has anyone done this type of testing with the correct equipment, would anyone else like to know?