OK ... So nobody has answered you , I will get onboard. 1st question. As the gun sits ; can it fire ammo ,Now? Is the gun complete ? 2nd . What ammo are you using ? 175gr may be too heavy or too long for it to cycle. 150gr ,155gr or 168gr may be the ticket you could try. Please DONT start messing with the gas port yet ! Also the RRA have (different size/type) buffer and buffer spring combo's than DPMS and Armalite. BTW, RRA is not know for their speedy service.