Many years ago, just to see if it would work, I trimmed some .30/06 brass down and tried it in my Colt Government pistol. The first problem is that the inside diameter of the case is .44 caliber not .45, so the case had to be reamed. The second problem is that the rifle case is not tapered towards the rim as is the case with a .45 auto case, so it might be harder on the pistol's extractor. I fired a few to rounds to convince myself that it could be done, then went back to using the correct brass.