I think you will find cartridges use the powder more effectively
A.45 ball( .440,.445,.447) weigh in the 130 range. A .36 about 65, .45 130, .58 260 I think this doubling of weight was the reason those calibers were common)
Anyway a 45 with a 40” barrel will get 1924 fps on a g-o 70 grain 3f load, 27 fps per grain.
A 230 grain maxi ball, a little shy of twice ball weight and around half of a 45/70 gets 1686 fps about 24 fps per grain. But when we look at muzzle energy we see a different story. Ball loses energy quickly. So even though we don’t shoot deer at the muzzle this number tells us how well the charge was used.
A round ball gets 1091 ft pounds of 70 grain, 15 ft pounds per grain of powder. Where as the maxi gets 1449, 24 ft pounds per grain of powder
It takes a .54 to get an old style minie ball in 45-70 weight range. 410 grains in old style minie.
70 grains gets 1249 fps, lower velocity then the 45-70 but not a big loss. And at 1418 ft pounds it comes in lower than the smaller maxi in energy.
The 45 is able to convert powder energy to bullet energy better, sort of. You have to throw in a bundle of other factors. But even if you loaded ball in to a cartridge your performance in terms of velocity and Ft pounds of energy would be up over an ml
