Finish Capture 1937 Tula Nagant revolver?

[Mp40Bran]

Here we have a 1937 Tula Nagant revolver with a Finnish capture marking. I not familiar with SA marking on a Nagant revolver. Could you please tell me if this authentic? If so is this a rare item? Thank you everyone for your help!

[Mp40Bran]

more pictures

[AndyB]

I am not expert on Nagants, anyway cylinder is different sn as frame, looks like cracked on barell area, possible some refurbishment done in time, black paint? b.r.Andy

[herd118]

Well worn Finnish capture, mismatched cylinder, that’s not a crack on the frame - it’s the indexing mark for the ejector.

[Mp40Bran]

Thank you guys for your help!