Don't use Winchester Wildcats. Don't use Remington. Do use CCI minimags or better yet, the newer CCI AR Tactical. Don't use standard velocity, do use high velocity. Loosen the flash hider, punch the rear take down pin, turn the bolt speed screw in about 9 to 12 complete turns. As set from the factory, the screw is flush with the rear. Turn it in about a ballpark 3/4 of full travel. A ballpark twenty full turns is about it's range. If you email the customer service people, they should be very polite, and they may expand on my list of ammo to use and not use. I might have experienced the sane case as yours. Customer service email response was helpful and I resolved my instances where I had failure to fire or cycle properly. Yes I know it may be advertised to fire standards, in my case I shoot the high velocity and have much better results. That's a bummer for me, because I bought the rifle expecting I would use standards in for best accuracy shooting steel chickens. I use it as a really fun gun to shoot plinking as well as paper target matches with friends and family. The guys love it when I load up a couple 30-round magazines and hand it over to them for a try.