Semi

I am not think that is a MK-85. Reason the left side of the receiver is not correct to be a MK. On a MK the left side of the receiver is closed. Also it appears to be a round receiver instead of a flat top.

This picture somewhat shows the receiver of a MK



There was a series of rifles after the MK and before the first Wolverine that it could be - but I am not familiar enough with the evolution to tell you for sure the exact models.

I would guess it were in the LK series but could be an American Knight or even a Black Knight.

Just not sure