Hey guys. Im not new to my Mosin Nagant, but i tried to remove my rear sight base, and im stumped My Mosin is a 1938 round receiver Izmash, and instead of two retention pins that need to be drifted, there's nothing! If you lift the rear sight, behind the spring on the base itself is a small screw head. I couldnt unscrew it. I know many bases are silver soldered on, but why no pins?