This is from the Hodgdon reloading manual online for the 335 CPB LFN CG:

Lil'Gun .452" dia 1.680" COL; 17.0 gr; 1,052 fps; 20,100 CUP
20.0 gr; 1,206 fps; 29,600 CUP
My opinion is a 255 gr, 18.5 gr 2400, up to 280 grain cast bullet, 10 gr Unique at 1050 fps is more than enough. Once you have two holes, how much more can a bullet do? The first load is the old Elmer Keith load which I've used on big pigs, the second I used on cow elk. Not a big sample but useable in S&W 25 in the first case, if actually hunting and the second all the time in a Ruger Bisley 5.5". You mention a .45 Colt but if the gun is not a Ruger or modern S&W, I suggest 9 grains of Unique and 255 grain cast SWC or LBT.