I recently bought my first two S&W 1917's (Brazilian contract models)and it has been an eye opening experience.
So here are some thoughts-
Order a back issue of Handloader #306. Therein you'll fins a great article by Brian Pearce on loading the 45 AR, that includes over 400 loads.
Both of my 1917's have large cylinder throats at around .454", and this is pretty typical from what understand. These also have rifling that is fairly shallow. This combination doesn't work so well with soft bullets unless you load them to pressures significant enough to cause the bullet to obturate, and even then you're liable to get leading unless you can balance the matter of enough pressure to obturate the bullet while keeping velocities low enough to prevent leading. Mine actually shot fairly well with a box of old balloon head factory loads I found-
I found I can use .452" sized cast bullets successfully if I water-quench them which hardens them to around 22 Bhn. Good accuracy and no leading, so if you're not a caster, order some hard bullets. I used 4.3 of Hodgdon Clays and 4.9 grs. of IMR-Target with a cast 228 gr. RN to duplicate the original 45 ACP load. Other than that, any powder one would use in a 45 ACP will work in the AR. I personally see no need in Trail Boss in this cartridge, but if that's what you wish to use, more power to you. And FWIW, I checked the water capacity of my Starline 45 Auto Rim brass against 2 or 3 different makes of 45 ACP brass and their capacity is all but identical which means data should pretty much interchange.
RN lead bullets are a bit more accurate for me, but cutting the forcing cone to 11° helped accuracy with SWC's.
One can shoot using 45 ACP brass without moon clips, you just have to pull empties out of their chambers with you fingernails.
Finally, though these revolvers are old, Mr. Pearce points out in his article-
"There are no "weak" .45 ACP revolvers, as even vintage U.S. Model 1917 Colt and Smith & Wesson revolvers have proven completely adequate to handle these pressure levels, while all modern guns are rated for +P pressures."
Hope this helps.
35W