04-20-2019, 04:45 PM
I'm back with an update. Sanders Armory took awesome care of me, and told me the reason I was having clambering issues was the previous owner of the upper replaced the bolt head with another brand. They replaced the bolt head, and said they dry cycled 2 magazines without it locking up. However when I received the upper, I'm still having the same issues. But in looking closely at the differences between my 5.56 upper and the 6.5, the magazine ears are being pressed into the shoulder in the upper receiver opposite the ejection port. That's why I'm having to force the magazines to seat. However the magazines do not have this issue in the 5.56 upper. So I'm getting the feeling either my upper or lower receivers are out of spec. Is there any way to tell which is giving me trouble?