If you use a PRB then the shot has to be a "broadside bow shot" < 50 to 70 yards in my opinion. The penetration is there with these projectiles but the mass is missing. I now shoot Speer Gold Dots in my TC Hawken 1:48 twist, with crushed rib sabot and limit my shots to 50 yards. I would like to get a Renegade Stock and buy a 1:28 Green Mountain Barrel for FL hunting. It is really about shot placement with just about any projectile, however some bullets allow for poor placement by going thru bone and tough stuff to get into the vitals. I think the heavier PRB can do that, the .45 can't from my experience in shooting a .45 cal FL for a while. I like the .54with a PRB, much more energy.
Chap Gleason