I read the RAA thread, but it doesn't seem to be my problem.  I have no problem with the rear section.  It seems like I need to take a little material off the front section of the upper.  You can see the two receivers touching in the front before the upper comes close to mating with the lower.  I have in my mind to take a dremel and shave just a hair off the upper from the front take down pin to about two inches back.  I can get the two halves to mate if I set the rifle on the floor, push on the top real hard and tap the rear pin in.  I don't like doing this.  This is a new stainless barrel and I want to "break" it in.  And not be using punches to take it apart and pounding on it to get it back together.  Is this a good idea?  Or a bad idea from the get go?

I had a similar problem with a new RRA lower and a Doublestar DS-4 Carbine kit.  I had to file just a small amount (about 10 strokes with the file) on each side of the rear takedown lug on the upper.  I then painted the exposed metal black and was in business.  It is a tight fit that does not rattle.  I rather have the fit oversized than have to resort to the Accu-Wedge.

My rear lug is not the problem.  This thing gets tight before the lug is in the lower.  I keep thinking shaving a little material off the front of the upper would solve the problem.  Since the old upper would go on just fine, though it was tight, I'm wondering if the new upper just needs a little help.  I don't want to shave anything off the lower.