i've ordered a stag 5h upper in early to mid november, finally got it a week or two ago.... it did come in as the 1-11 twist which is a plus. but when i cycle the charging handle a few times the forward assist button comes/falls out. is it the roll pin installed wrong? is there a missing button stop? it funtions fine but it would fall out with the charging handle cycling. i dont have funds for a sight/optics yet so all i can do is break it in with the cycling.