This appears to be a spotting rifle built on a Moisin-Nagant action.
The recoil mechanism is obviously factory-made, but the rifle itself looks like it was adapted from a standard infantry rifle taken out of service, rather than factory-fitted. The lanyard ring that replaces the trigger is welded on with little attention to finish. The magazine well is plugged by a well-fitted steel plate held in place by 3 rather crude tack-welds. The barrel near the muzzle shows a shiny spot where a front sight has apparently been removed.
I haven't removed the recoil mechanism to look for hidden markings, but the only markings visible are 3 Cyrillc letters and a tiny crest I can barely see, let alone identify. There is no date, no serial number, and no SA marking.
Does anybody know what gun it might have fitted? Maybe it's better if I don't find out. I might be tempted to buy the gun to go with it.
Or maybe it's not a spotting rifle at all. Can anyone think of what else it might have been used for?