I've run at least 1,500+ rounds thru this carbine with no problems, then it started have light primer strikes. Changed ammo, still intermittent light strikes. All ammo runs fine in all my 9mm pistols. Made sure barrel nut proper;y tightens - no change. Disassembled and ran everything thru an ultrasonic cleaner, reassembled and lubed - no change in strikes, but now started intermittent doubling, firing 2 shots for one trigger pull. Disassembled and made sure everything, including trigger assembly, went back together properly - no change. I'm going to call Ruger next week, but anyone with any ideas?