I have seen a couple people ask similar questions but haven't really seen a answer and I'm new to Automags. I have ULE Mag with X-Valve and every so often I will be shooting and my bolt wouldn't go all the way back and the marker won't fire. All I have to do is slightly push the bolt back and it will be good to go. The marker doesn't usually leak when it happens like I have seen some people say, the only way I got it to leak when it did it was when I loosen the screw on the side that holds the sear in place. So I didn't know if its the bolt spring or if the sear is getting stuck on something.