I have an issue with my AR going through anywhere from 15 to 25 rounds in a mag before it drops the hammer on a round without setting it off. Sometimes it will empty a whole mag and other times it will have this FTF. The gas key is staked and not moving and all of the gas rings are new. I do not think that this issue is a gas system problem because it functions just fine on semi with no FTF problems. I have heard that this can be casued by a recoil buffer spring that is too strong. Any help would be appreciated.