I bought a rebuilt S&W M-1917 shooter. !917 frame, new .45 ACP 6.5" barrel, cylinder with a different SN than the frame and reblued.
Single .45 ACP are stopped in the cylinder by the case mouth headspacing in the chambers. No problems with "full moon" clips, but I decided to go with Starline .45 AR brass and HKS 25-M loader. The HKS loader aligns the cartridges OK, though it doesn't insert them very far at all as the ejector center stops it with the boolits just entering the cylinder.
But the biggest problem is trying to load all 6 .45 AR cartridges. The cylinder will close with 4 rounds loaded 2-blank-2-blank. As soon as a fifth or all six are attempted, those cartridge cases stand out far enough from seated to prevent the cylinder from closing.
Could there be enough difference between the 1917 cylinder and the 1955 cylinder? I can't see the 1955 cylinder not working with Auto Rim cases. The cases lock into the HKS, so the rims wouldn't seem to be that far off (if at all). And I've used lots of Starline cases and have never had a problem with them - certainly not enough of a problem to see this sort of issue. I guess it could be another "N" frame cylinder rechambered to .45 ACP, but that seems like a dumb thing to do.
Any bright ideas on what the cause might be? Right now it looks like I'll have some new .45 Auto Rim cases for sale soon.