792mauser,... I load 45 Auto Rim for my S&W 325PD ultra lite with full lead wad cutters and Trail Boss powder. I would have to double check, but, I believe Auto Rim brass isn't loaded any different than regular 45acp brass. I load all my straight wall, and some bottle neck calibers, with Trail Boss Powder, to produce very safe light loads, even at max capacity.
If you follow the load data for Trail Boss and start low, as recommended, you should realize just how safe the loads are, very quickly.
After many pounds, and many different calibers, for many years now,... I just go to max load and don't think twice, even with a new caliber, I have not loaded for,... that is how safe Trail Boss powder is, to me. Some guys don't like Trail Boss powder because it looks and measures different from ALL other powders, but, I have no problems and actually like it better because of my single stage press, one at a time, hands on

loading style.
You may want to give it a try, I can't think of many other powders, for your specific situation, that would be as good.