Have a factory assembled LMT carbine upper that I have had for a year or so. Put several rounds through it with open sights and a cheap red dot. Figured my accuracy issues were with the fact I was new to the AR platform and the open sights and low quality optic. Well, about 3 weeks ago my wallet puked up money and I bought a Browe BCO acog. The damn thing would not hold zero to save its life. 3 trips to the range and frustration and blaming myself.
Well today I decide to call Browe and ask the owner Brian about sending the optic to him to have them look at it and see what the heck is going on. He said send it in asap and he will have a new one out to me within 24 hours. He then tells me to check my barrel nut. Hummmm,,,,, Barrel nut? Never thought to think of that because I purchased a factory assembled high quality upper and barrel. Well I will be damned, the damn nut was finger tight. How I never noticed this when cleaning it or shooting it I will never know. Kinda pisses me off really. Not even close to torque specs. After removing the gas tube, I spun the nut off by hand. No way this could have happended over time because the way the tube holds the nut in place.