50 caliber minimum for elk in CO, and you'll have the best selection of bullets in 50 cal. so that's what I'd recommend unless you want to shoot round balls, then something bigger would be better. If you don't know the regs, no scopes allowed, fiber optic sights are OK, no sabots, pelleted powder, or smokeless.
I use a T/C Triumph, light and handles good. I use 348 grain powerbelt bullets because they're accurate and easy to load. You'll have people tell you they're no good for elk but I think I've killed 8 or 10 with that bullet and none got away. Saddlesore uses 'em too I think. I think some have had less than optimal performance with lighter weight PBs.
I use Blackhorn 209, great stuff and not nearly as hard on the bore as some other powders. You need a hot primer for it though, 209 only. Hope this helps.
\
New for 2018, if you want to shoot round balls you must use a .54 or greater...
