A 16 bore will make 2650-3000 at the muzzle with 110-140 gr of FFG Swiss. But as Daryl posted its just a number. With BP and large diameter balls its really meaningless.
They will kill large animals very well to ranges of 150 yards or more though the energy level is far under what the "moderns" with their little copper jacketed slugs think is needed.
The 50-54 cal rb will shoot through and cleanly kill deer with broadside shots at retained energy levels most modern hunters would scoff at as useless.
The modern small bore copper jacketed bullet, especailly teh spitzer type, must expand to produce a 50-75 caliber wound channel. The round balls of 50-75 caliber need not expand to produce a big hole.
If the spitzer does not expand it make a very tiny wound channel that will not kill quickly inless it strikes the heart or a major artery. Expansion requires high impact velocities/energies.

Dan