My S&W "AR" M&P 15t jammed a dozen or more times today and I need help curing it. It worked fine the first 60 rounds but jammed frequently after that with both AR Stoner and Pmag magazines and PMC ammo. Each time it jams, pulling the charging handle back and releasing chambers the round. If I look at the jammed round, the point appears to be caught on the loading ramp(s). I clean all my guns after every use and wonder if a better job could be done on this area with some special brush... I've been using a toothbrush shaped brass brush up until now. Will lubricating some area help?