4-Sigma Bullets and Ammunition greatly reduce noise and recoil so that flinching is essentially nonexistent. You are therefore free to concentrate on developing the proper sight picture and trigger control. Firmly imprinting these concepts on your mussel memory is a prime objective before gradually increasing bullet weight and powder charge toward full loads.
The .45 Colt loads can of course be used in a .454 Casull.
A word about self defense: few people are interested in killing another human, intruder or not; and, few intruders are interested in getting shot. Yet many bullets available for self defense are specifically designed to enhance killing power. 4-Sigma Bullets will certainly put a heck of a hurt on the bad guy but are much less likely to kill.
See Relative Recoil.