On the topic of 80grs. Swiss being hotter than 80grs. Goex I simply don't know but since BP is measured by volume rather than weight I can't imagine the big differences in impact on the shoulder or target but you did the shooting, not me.
120grns fffg behind a round ball is the regular hunting load around here for hunting Indiana whitetails. there are 3 54's built off of robideaux prints with sharon 36in 1/72 flat rifling barrels. My rifle has a .62 Sharon barrel built the same way. I shoot 140gr fffg.
all these guns recoil and can give one a sore shoulder after about 20 or so shots with light clothes but based on experience we consider this a minimum for 100yd. shots.
85% or so of the 25 (give or take a few deer) shot with this load showed no exit wound(maximum energy dissipation in the animal) and most shots have been well under 100yds. It will break ribs and shoulders on deer and they generally run less than 75yds when shot in the chest.
elk are another matter---recoil or not--80grns, even 120grns. behind a 230gr. round ball would not be my choice for an elk at any distance. ballistically you're down to 966fps at 100yds and 473fpe with 80grs and only increase to around 600fpe with 120grs.. In my opinion If you hit the shoulder or a rib you're going to have a good chance of loosing the animal.
The 54 *is* problematic on elk if large bones are hit, though a rib is not a large bone for this discussion.
There is a poster on this site who watched a hunter kill a Canadian moose at 175 yards (lasered) with a 54 with a 100 gr or so of P-dex. Ball penetrated to the offiside hide Moose only went a few steps. I thjnk he is in hunting camp at this time.
I have broken a large bone with a 54, the humerous, mid-point between the joints and still killed the elk. Ball shattered the bone and then holed a large artery just above the heart. Range was about 75-80 yards. But the ball was well spent and had it not gotten the artery or heart it might have been bad.
I did nearly the same thing on a Mule Deer with a 54 pistol at about 25 and the ball was under the hide offside after getting the heart. Neither animal made over 50 yards and the elk was knocked down for probably 15 seconds.
There is little to gain in a 54 using more than 100 grains of powder. The use of Swiss FFFG can reduce this another 10-15 grains and still produce sufficient velocity to kill most NA big game to 100-150 yards.
Bullet energy is mostly meaningless in BP firearms and others using slow moving lead bullets. Compare a 45-70 BP load with a 243 and you will get my meaning.
I built a 16 bore rifle (.662 ball) for a couple of reasons, one was elk.
Dan