I got this rifle from a guy in a trade and the upper wasn't completely assembled. I had to get a bolt and carrier, forward assist, charging handle and trap door/ dust cover and install them myself. I also checked the head spacing on it too. The ammo was new Remington 223 55gr brass, but there’s no grantee that it was good I have had some bad one before in other calibers but not often. Other then that the rifle was fully clean and lubed. I will send a pm to Marlin and see what he has to say. Thanks