Issue description: I can't figure out what's wrong. Far as I can tell it seems to be binding on the mag release catch. I double checked assembly and everything looks right - bolt forward, dustcover aligned to rear, recoil tube tab at 12'clock. I insert the op handle, move it forward... There's a click as the bolt head goes over the mag catch... And then stuck. I have not forced it since I'm not sure. Firearm has had about 400 rounds through it. Model is su16ca from about 2006. Yeah, it's been a safe queen for a long time.