It doesn't matter what gun a given bullet of a specified weight or diameter comes out of, but rather the muzzle velocity. The 230 gr Lee RN bullet fired out of a 45 colt or 45 ACP at 950 FPS will maintain 871 ft lbs of energy @ 100 yds with a bullet drop of 9.3" if zeroed @ 50 yrds. Now, if it were sighted in @ 100 yds, it would be 4.65" high at 50 yds.
The general rule of thumb is 1000-1500 ft lbs of energy to kill a deer at a specified range, but the 45 colt almost never reaches that at any distance, but is one of the better killing calibers out there for shots less than 100 yds. It doesn't matter what it looks like on paper, the 45 ACP @ 950 fps will kill a deer at 100 yrds if it is hit in the vitals. The 45 colt has been around since the 1870s, so its seen some service, and again, its the speed of bullet travel and the weight/diameter that determines energy and bullet drop/raise, with bullet coeficeint added in the program to keep the computer honest and thinking.
I use these ballistic programs on my cast bullet loads in over 20 calibers and they are damn close. Again, a 45 caliber bullet is a 45 caliber bullet, no matter where it comes out of.
That being said, I would use a min of a 230 SWC of FN lead cast bullet, as expansion is not an issue due to the diameter.