I know this is an old thread but thank you for the information. My R1 never did until last Wed and did it twice at the only Elk I saw on a 5 day hunting trip. It fired as the Elk were running away and at 450 yards. Yes I took a shot out of frustration and to see if it would even fire which it did too late. I would have never thought to clean the gas piston considering I have less than 60 rds on this without an issue. It really sucks cause In the unit I hunted the Elk are about to be wiped out by the states introduction of wolves so Elk are getting harder to find.