I am working on building my first AR15 upper. I have a CMMG upper and will be mounting a Daniel Defense Lite rail on it. The Daniel Defense barrel nut does not thread onto the upper easily by hand. It goes on easily for the first 3-4 threads, and then gets pretty tight. I can't get it on any further by hand. I don't have the proprietary DD wrench yet, so I'm not sure how far it would go on with the help of a wrench. I should have the wrench in the next few days. This is without the rail or barrel in place - just test fitting the nut by itself. Threads on the upper and the nut look fine. I am wondering if this is normal, or perhaps did the anodizing on the upper go on a little thick?