Now that all depends on which muzzle-loader you are using. I've been using a Savage Model 10 ML-II smokeless powder muzzle loading rifle for the last 3 years and I'm here to tell ya, it's one seriously wicked white-tail whacker. My pet load (NOT a Savage recommended load!) is a .452" 300gr Hornady XTP-MAG over 68 grs of H4198. The bullet clocks at 2420 fps at the muzzle, generating 3900 ft.-lbs. of energy. This load will group 1 1/2" @ 100 yds if I do my part with the loading. Sighted 3" high at 100 yds, the bullet is only 10" low at 250 yds. That's about as good as it's gonna get for a state that doesn't allow modern high-powered rifles for deer hunting.

2nd day of deer season in 2007, I crushed a doe (I had already gotten my buck the day before) from a measured, and witnessed, 244 yards with this rifle/load off a set of Harris bi-pods. Bullet broke the near shoulder and one rib going in, took out both lungs, sent bone fragments into her heart, broke two ribs and the other shoulder on the opposite side and lodged just under the hide. She dropped right where she stood and never even kicked trying to get back up. Quick, clean and no tracking necessary!