I built this AR-15 upper in .50 Beowolf to go boar hunting, but never got the opportunity. It has been fire about 50 times. Recoil is more of a push rather than a slam. Spikes upper modified to eject spent cases, Magpul carbine length handguard, Spikes gas tube, bolt, gas block with pic rails. It has a 16" stainless barrel with muzzle break. It has two Alexander Arms 4rd mags and one Alexander Arms 10 rd mag.