I believe this is a 60 degree variant, but other than that, I'm not sure of it's heritage. First picture shows the only place I can find anything that might be a marking (to the left of the serial number).
![Image](https://farm2.staticflickr.com/1671/23824409772_93f3b525fe_b.jpg)
![Image](https://farm6.staticflickr.com/5732/23932687825_c30dd04ede_b.jpg)
![Image](https://farm2.staticflickr.com/1641/23850205751_1b4e8f6b6e_b.jpg)
![Image](https://farm2.staticflickr.com/1611/23824422202_f5073f4bc4_b.jpg)
Good info! I am familiar with the Tula and Izhevsk marks, but not the Sestroryetsk mark. I google imaged it, and came up with some of your fine photos, of course.martin08 wrote:It does appear to be a 60 deg variant, which would narrow its production to the 1905-1910 era. So it would have to be a Tula, Izhevsk or Sestroryetsk.
There is a pretty large area where it looks like it has been scrubbed with a coarse file, possibly eliminating the maker's stamp.