6MM ARC upper thoughts on BCA vs

[300BLK]

I mated a 20" Faxon heavy, fluted barrel to a BCA sidecharge upper this morning. The NiBo barrel extension was snug going into the slickside receiver and needed a sharp rap to seat the last 1/8". This has been the norm with various barrels and receivers I've used including Vltor uppers. I had one that was a little looser and one that was little tighter.

The BCA 556 bolt was swapped out with a SixFive Outfitters bolt .