BP ammo in these rounds ran in the 2,500 to 2600 fpe range. Smokeless, of course, ran much higher. Of course, this sounds lower than their game performance dictates. Either will drop a buffalo with a proper hit, and did, out to 300 or more yards. They lacked accuracy due to too-slow twists, not power for longer ranged killing. A 24" twist, barrels available from GREEN MOUNTAIN or "TRACKOFTHEWOLF" will re-barrel to a proper long range twist that will shoot 1-1/2" easily at from 100 to 200 meters with BP or smokeless.(mine did)
: Either .50's are much more powerful than equivalent fpe would suggest. It is a poor indicator of killing power.
: It does have one use though. We know from experience it takes roughly 400fpe from a .17 to .22 cal bullet to easily dispatch coyotes without loss.
: 1/2 that fpe, from a .54 round ball penetrated to the off side of a bull moose, dropping it in 40yards from impact, yet it's 200fpe is 1/2 of what is considered necessary for coyote - that alone should dispell fpe as being anything remotely attached to killing power of large bore rifles.
: I do not know if there is such an animal as factory ammo for either. I suggest that there probably is, but on a custom basis only. These rifles are individuals and need ammo developed for them specifically.