Thompson Omega Range

[Tennessee Elkman]

I've been shooting this gun for about two years and really enjoy it. Bear and whitetail are no match for two 50 grain Pyrodex pellets pushing a Barnes 320 g bullet, however, now I want to use it on the opening week in Colorado for elk. If I go to three 50 grain pellets, what range could I expect from the gun. 150 yds? 200 yds? I won't consider a shot over 200 yds. with a muzzleloader simply because I don't trust all the variables. (IE. the shooter, wind, weather, etc.) Any help, ideas, or suggestions?