I just built a nice A4 type rifle using all RRA components with the exception of a brand new in wrap FNMI Govt. profile 20 in barrel. The barrel indexed nicely, gas tube alignment is suberb with no carrier key friction whatsoever when installing empty bolt carrier. Torqued according to TM with the 3X tighten loosen to 31 ft. lbs. Final torque when aligned was right near 65 ft. lbs. The end result was a very slick and excellently indexed & aligned barrel and gas tube.
I have one area of concern. The threads and barrel extension itself were properly greased with Moly B, but it was a very tight fit when inserting the barrel extension into the receiver. I heard an odd scratching of the aluminum while pushing the barrel into the upper. I had to utilize a rubber mallet on the FSB to get the barrel seated all the way in.
What concerns me is the aluminum scratching sound and tightness when initally pushing the barrel into the receiver. I've done many barrel installations while an active duty armorer, but never encountered this before. I wondered if you folks would consider it ok on a new rifle.
I should add, it was no problem tightening the barrel nut after I had the barrel on the receiver.
As mentioned, the barrel did install and tighten/torque up wonderfully. I bought the lower and upper complete from RRA, all I had to do was install the barrel. The end result is a nice RRA 20 inch A4 with new FNMI Govt. Profile barrel. Pretty nice set-up, but I guess I need some reassurance regarding the above issue.
Thanks for the help!!