Last night I was playing with my new Larue mount on my Stag 2t. With an empty mag and the bolt locked back, the bolt would occasionally close by itself. As I experimented more it seemed that if I put pressure upwards on the PMAG the bolt would fall. I ended up taking the upper off and then put it back on and I could not repeat this. I have a feeling that it could be a weak mag spring so I changed out mags just in case. I still can't get this to repeat. Any thoughts on what caused this to happen in the first place? Anyone ever heard of this?