They make such a 45 Colt load but it costs as much as the 454 rounds. Cor-Bon, Buffalo Bore, and several others produce "hunting" style loads but as they are relatively low volume, the price is kind of steep. If you are shooting the 250 gr Winchester Super-X rounds, you are shooting a fairly mild loading as it is equivalent to a hot 45 Colt. This is the load I regularly use for antlerless deer in slug/handgun zones as it is so easy shooting. The 300 gr soft points from Winchester that have been discontinued are along the same lines as the original 454 loadings by Freedom Arms; those will get your attention much better. I shoot a lot more 45 Colt rounds through my RSR than 454 as they are much more pleasant to shoot and less likely to have squib loads as the powder takes up more space in the case.
As for wearing out a RSR, that may take some doing but I believe it can be done if using full power Casull rounds. It is well known that the Ruger cylinder "flexes" a little when true 454 Casull loads are used. This often causes the cases to stick in the cylinder and makes for difficult extraction. This is one reason Freedom Arms has a 5 chambered cylinder rather than 6. I have to believe if the cylinder is stressed then other parts must be too though it is anyone's guess as to how much and how long the gun can handle this. As I mentioned, I shoot a lot of 45 Colt rounds which, even at their hottest, are much less stressful on the gun than most 454 loads. In this case, I expect the gun to outlast me by a large margin.