Regarding the 45 Colt, I run a 285 gr. (RCBS 45-270 SAA mold) just shy of 1000 fps out of my 4 3/4" Uberti that meets the 500 ft. lb. mark well past 100 yds., and does so with only 9.5 grs. of Power Pistol. Point is, it isn't a difficult criteria to meet nor does it require a loud, heavy load.