I picked up a common 1910/1914 6.35mm the other day just because it had not been messed with and it looked pretty clean. All matching numbers, nice grip, good bore, functioned well. When I was stripping it down for a good cleaning I noticed on the left side, on the back of the trigger guard there was a #1 that I had not seen. I never looked for a number here before on these guns. Dug out my Roy Pender book, looked around online. Nothing. Unit marking? Any ideas?