Odd, I regulary shoot lubed cast boolits over 2,000 fps in several rifles and do not have a leading problem.The reason that you should use jacketed bullets in loads going 1600 FPS is because if a lead bullet travels down a barrel at higher velocities it tends to deposit lead in the bore. With blackpowder leading isn't much of a problem, especially if the ball or bullet is in a patch or sabot.
Cabelas sells sabots .452 diameter pistol bullets, those should work just fine with a .45 Colt bullet.
Levi
I don't know why some mention bore leading. Since you are using sabots and the bullet will never touch the bore, leading is not possible.For 240-300 grn pistol bullets in sabots fired from a muzzle loader would 45 Colt bullets work or would 454 Casull/460 S&W bullets be needed since they are traveling at 1600+ fps?
Not very well.I've also wondered how a 45 ACP FMJ would handle traveling at such speeds and striking a big hog.
Way too soft!They have a BH of 7-11.