Thank you very much for the replys and to let you know I learned a exspensive lesson that i will not make the same mistake. In tightening the barrels nut enough to line up the gas tube slot I accually cracked the upper I had it in wood up close to the front, but I screwed up lesson learned, working on AR's is still new to me and I will conquer them. ONce again thatnks for the replys.