From what I've read, this 1941 Tula rifle started as an SVT 38 and was rebuilt to SVT 40 specs (from the square stamp on the receiver). Then it was refurbed with a 1943 Tula AVT 40 stock. Lots of WW2 history here.
SKS for scale:
Square supposedly indicates rebuilt SVT 38:
Late muzzle brake and sling swivel:
AVT 40 stock - note dual cutouts at bottom:
Bore looks perfect, can't wait to go to the range!
SKS for scale:


Square supposedly indicates rebuilt SVT 38:


Late muzzle brake and sling swivel:

AVT 40 stock - note dual cutouts at bottom:


Bore looks perfect, can't wait to go to the range!