Glad to hear you found it to be only an ammo issue! I can't believe how many times I've read about other guys paying $1500 for a rifle then complaining when it won't function well or shoot sub MOA with cheap steel cased bi-metal FMJ Hungarian ammo. I say, man, would you feed your best Labrador retriever the cheapest low grade dog food you can buy, & then complain when he can't hunt the pheasants 'cause he's too busy with the sh--s. (By the way, studies have shown that shooting bi-metal bullets can reduce barrel life by over 50%.) Our M&P10 barrels have a proprietary barrel nut. Thus, to replace a worn out one, we're going to have to buy it from S&W. Not sure, but me thinks it's Not going to be cheap.)