I just received A RRA upper for the my first AR build. On the barrel are the markings" W 9 A ", I assume that " W " stands for Wilson and the " 9 " is the rifling twist rate, but does anyone know what the " A " could stand for. The Upper is a standard A2 RRA.
This is the first AR that I've ever owned and I built it myself, what a rush...loads of fun. I'm already planning my next build and want to assemble the upper myself this time.