In short, almost everything I have. I tried it and it fits great in the following:
- 1918 Erfurt frame (9mm Artillery shooter)
- 1918 DWM (9mm shooter)
- 1906 American Eagle 9mm (s/n 55xxx)
- 1906 Swiss Cross in Shield (7.65mm)
- 1913 Erfurt (9mm)
- 1920s Commercial Safe and Loaded (89xxx) (7.65mm)
- 1906/34 Portuguese GNR (7.65mm)
Two guns it was a bit tight in (at the end of its travel) were both a 1906 and a 1908 DWM Bulgarian contract.
I previously reported that the drum would not fit into my 1920s Alphabet Commercial, but found that the issue is the right grip screw. If I back the screw out half a turn, the drum goes in fine and locks securely into place. I'm thinking the grip itself is a little thin on that side.
I even tried the drum in a couple of my Old Models, but couldn't get it to insert very far at all. I guess I need to try backing out the grip screws a bit on those.