Okay guy, I am not getting any hits in the build forum so I am posting this here.

Details:

 I bought TWO "mil spec" C7 uppers from Fulton Armory last week for my Pony builds I am doing.  I couldn't get real C7 uppers so I ordered from Fulton becuase they have always done me good.

 Well, yesterday morning I got bored and decided to test fit the bolt carrier setup and charging handle to my un-assembled uppers.  Not a single one of my Colt or USGI chargining handles will fit in the track on EITHER upper.  I can switch them between any of my Colts with no problem but not one of them will fit in the track of the new uppers.  Before I send these back I want to know: does an upper need the barrel assembly cranked on to pre stress the upper receiver or do I have bum uppers?

It sounds to me like they are out of spec.  I can't see how having the barrel installed would make a difference in whether the CH is going to fit or not.

Brian

I just have to know for sure.  These are gorgeously machined receivers and I am REALLY bummed they are bum.  Fulton should be opening soon so I am gonna call them ASAP.

What did you find out???

Okay, mystery solved, I spoke to Fulton today. They have had a few issues with this and it is a vendor problem. The upper charging handle track is out of spec. I have already ordered two more but this time they are gonna install charging handles in the recievers ( I ordered them with charging handles ) and double check them for general overall quality for me.

I have to say that the recievers were VERY pretty and nicely machined as far as general fit and finish....I hope hoping the next set is as nice looking....and better fitting in the charging handle department.

I had figured that installing a barrel had absolutely nothing to do with it...however there are stranger things in the world and because I have never built an upper before I really wasn't sure of there was something odd that I might be missing.  I thought it a distant possibility that the reciever might have to be pre-stressed by installing the barrel nut.  Silly....but I have seen wierder things.

Glad you got it worked out.