How many rounds have you fired thru this gun? Same type of ammo? Sounds like the ammo doesn't have enough poop to cock the hammer,altho it has enough to cycle the bolt. Try other types of ammo. Personally, I'd pull the barrel, true up the polishing point of the Dremel, and do a couple of revolutions of the sides of the chamber. Many .22 auto chambers aren't nearly smooth enough for trouble free ejection. If there's too much resistance to the fired case's extraction, it can throw off the timing and function of any autoloader. So I start there with a "problem" autoloader,( if it's not a magazine related malfunction, anyway), expecially with a .22, and especially if the barrel is easily removed