I've only killed deer with the 255gr RFN over 8.2gr of Universal for ~900fps.
It was way more than needed. Complete penetration on angling frontal shot. Entered left shoulder and exited right ham. double blood trail for ~25feet. (125lb doe).
From a friends Taurus Thunderbolt or my Winchester M94 "Legacy", they shoot ~1" at 50yds and sound like a "bass" .22lr (deeper sound with slight "crack" from 1,100fps).
There's a reason that "Uncle Sam" reduced the original load from ~40gr of BP to ~28gr of BP. Still enough for intended purpose/use; less recoil and better accuracy.
Next time I shoot a deer with .45Colt, it'll likely be with a 200gr LSWC (.45acp target bullet) at ~1,000fps. Very, very accurate.
Over 70gr of Pyrodex w/sabot from .50cal m/l, I've killed several deer. Two -dead right there- with the 200gr SWC. Less lead, less recoil, lighter weight-less expense of lead. (good w/w getting harder to get...).
Last year, I took .45lc to Colorado on elk hunt. To make the gun "legal", I carried the 270gr RCBS SWC, over 11.2gr of LongShot for ~1,125fps. Way, way more than needed for deer. After returning home, I resighted it for same bullet over 9.2gr @ 900fps. Still more than needed for deer but just-right for pigs that may run a bit heavier than deer.