358Scout,
I've tried shooting IHMSA Rams with my 6" Bar-Sto bbl. Ser. '70 .45ACP, and dust kicks up just past 100 yds. . Being one of the few Marlin Camp Carbine .45ACP owners, as few were made, and they didn't make them for long, I and a few friends could consistently take down Rams , and everything else, with the Marlin .45 EVEN with 200 gr. LSWC 68's . My JR Carbine also knocks them down consistently.
Admittedly .45's, .44's, 'hot' .357's, aren't exactly 'flat' shooting, so aim at the top of the Rams back, but that longer barrel WILL get them out there ! Hard to believe, I know, but a friend of mine actually took down FOUR ram's in a row with a FOUR inch S&W mod. 66 .357 ! Witnessed (in complete SHOCK) by many , but proving it's the SHOOTER and NOT the gun ! However, with the slower moving .45 from a pistol, it's pretty much the GUN/cartridge !