If you want that kind of pressure from a 45 Colt why don't you just use a gun designed for it like the 454 Casull?
It seems foolish to push the round beyond its safety margin.
That kind of pressure is well within the safety margins if you use a Ruger Blackhawk or FA 97. The "Ruger only" loads are still well below 454 pressure.
45 colt (Ruger,FA,TC only load) Max load - cast performance 360 gr and 21 gr of H110 is 28,300 CUP
454 using the same bullet and a max load -
24 gr of H110 is 43,400 CUP
Pretty significant difference
Using the same logic one could ask, why drive a bullet from the 454 at those pressures when you could get a 460 S&W? Same thing, 460 S&W pushes with more pressure. Plus the 45 colt in Blackhawk and FA can be had in a smaller frame than the 454, which can be had in a smaller frame than the 460 S&W. It's all about compromise.
Super Redhawk 454 with 7.5" barrel weighs 53 oz
Blackhawk 45 Colt with 7.5" barrel weighs 42 oz
That is nearly 3/4 pound difference, also significant.
My 4 5/8" Blackhawk weighs 36 oz and is more powerful than my 2.5" barrel Super Redhawk 454 that weighs in at 44 oz. Guess which one I'd rather pack around the mountains?
Finally, the question was not "Why shouldn't I load the 45 Colt to its full potential and what should I get instead?".