I like the flared mag well.... I don't own one so I can't say it happened to me but I have heard over the years you must keep the pins from moving on a poly lower.... I would suggest the KNS non rotation pin setup.... It's cheap and effective... I would really be interested in the life span vs the stock metal lower.... The weight saved alone would be great , ounces lead to pounds and pounds to pain... All of my ARs are to heavy to me and I really tried to keep them light BUT strong , it's hard to do or should I say it's expensive to do correctly....