I tested loads in my M1917. Because it is a prewar WW2 pistol, it needs large bullets to avoid leading. The barrel diameters are large and I had leading with 452 diameter bullets. I found commercial cast bullets at 454 diameter and these gave better accuracy and reduced leading. Bigger is better in these tubes.
Ignore any Elmer Keith loads, they are not appropriate for this era of pistol even if he used them. I found much later that the typical WW1 era pistol was not heat treated, the barrels, frames, cylinders are dead soft plain carbon steel. They won’t hold up to hot loads. Elmer recommended a 250 grain load with 6.5 grain Unique, and that was way too hot for this pistol. I tried 6.0 grs Unique, and 6.5 grains Unique. In this lightweight pistol I found the recoil excessive, especially with the 6.5 grain load. Back in his day, those pistols were cheap and Elmer could replace one easily. Now they are collectables and gunsmiths don't know how to work on Colts. I would recommend keeping 230 grain loads at or less than 800 fps. An excellent load in my autopistols is a 230 Lead, 4.5 grains Bullseye, any case, any primer. For a 230 FMJ, the classic load is 5.0 grains Bullseye. For 250ish grain bullets, keep them 750 fps or less.
I got tired of loading and removing fired cases from moon clips, for me, the best solution was Auto Rim brass.
Because I shoot 45 AR loads in this M1917 and a converted MkVI Webley, I now use a load of 255 LSWC and 3.5 grains Bullseye. This is a very mild load, shoots well, and does not stretch the top strap of the Webley.
M1917 S&W Brazilian Export 5" Barrel
250 LRN (.454) 4.5 grs Bullseye thrown, R-P AR cases, CCI300 primers
20-Jan-02 T = 44°F
Ave Vel = 754
Std Dev = 10
ES = 39.5
Low= 744
High= 783
N=14
Mild recoil, aimpt 5 OC, accurate
