This upper has never jammed and holds a 2-3 MOA grouping in the right hands. All I did was break in the barrel it's got a lot of life left on it. Cold hammer forged barrel, BCM hand stop, yankee hill machine muzzle break, and the upper and lower are from an unknown manufacturer no serial numbers or markings of any kind aside from the caliber stamped on the barrel. The optic is a Victos LPVO 1-6 holds a good zero keep it or throw it away I'm not calculating the price of the optic in the build.