I traded for a RR flat top 16 inch upper at the gunshow, it's new. Got out to shoot it yesterday, here's how it went. I mounted a 3x9 scope on it using a Weaver riser and rings. Heavy but ok for initial testing. The first 20 round magazine functioned flawlessly but the first ten shots were stringing up and to the right. The next ten started looking like a group. The second magazine also functioned flawlessly and accuracy settled into my being able to hit bullet holes at 50 yards. I got the barrel pretty warm but not to the point of hot. Ammo is Federal XM193 55 gr fmj's. The 1 in 9 inch twist seemed to really stress these bullets as all broke up when they hit the dirt.
