I have yet to see a first variant 13-77 medalist in person. The 22 is more common around here, with them being seen for sale occasionally at gun shows.

Also, a first variant should have a steel piston rod with oil wiper behind the cup.

Give us a pic of the L/H side of the gun. From here it looks like a combination sling loop and rear sight were sweated onto the bbl. It may be easily reversible. The challenge will be finding the correct steel rear sight base.

Does it hold air and shoot?

We think alike on projects. Doesn't stop the acquisition thing with me in the least though...

Regards,

Doc Sharptail