now this is cowboy action cartridge load data, not loose powder in a cylinder- got that MADCRATE ?
FWIW, you can get more velocity with full cylinders of blackpowder than with a cowboy smokeless load- the Walker, ROA, and Dragoons will all easily go over 1000 fps with black/pyro/H777
http://www.handloads.com/articles/default.asp?id=37
38 Special, 4.0gr Traill Boss, Leadheads 168gr Keith, 1.506" OAL, WSP primer, Federal brass, 4" Ruger GP100
720 fps, Std Dev 24 fps, ES 63 fps
44 Special, 5.0gr Traill Boss, generic 240gr LSWC, 1.500" OAL, WLP primer, Starline brass, 4" S&W M29-2
797 fps, Std Dev 10 fps, ES 23 fps
45 Colt, 5.0gr Traill Boss, Black River 255gr LSWC, 1.650" OAL, WLP primer, Federal brass, 5.5" Ruger Bisley
832 fps, Std Dev 17 fps, ES 45 fps
IMR Powder
38 Special 158gr LSWC 2.7 - 4.2gr (13,700 CUP 800 FPS)
44 Special 240gr LSWC 4.0 - 5.2gr (11,700 CUP 763 FPS)
44 Magnum 240gr LSWC 6.0 - 7.3gr (21,600 PSI 917 FPS)
45 Colt 250gr LRNFP 4.5 - 5.8gr (12,700 PSI 727 FPS)
so the question becomes, if 5 grains of Trail Boss in a 45 Colt cartridge is safe, in a cowboy action gun/ROA cartridge conversion cylinder- what would 5 grains of "loose" trail boss do in the blackpowder ROA c/b cylinder, with round ball pressed over it, and a cap ?
that is something you test with a 100 foot long string, from behind a sheet of steel