RE: What gun is this?
Looks like a Mosin with the fore-stock cut down. The barrel seems too long for a model 44. If you can verify it's chamber to be either 7.62 X 54 or something else you can go from there with deciding how to proceed. Any reputable smith could do a chamber casting for you if you are planning on shooting it. That way you'll know the cartidge you're supposed to be sticking in it and also the condition of the chamber.