An existing rotating bolt but with exactly 1mm of the rear of the locking lugs filed off. This allows gas to flood the chamber past the locking lugs to the bolt carrier with a head that acts as a gas piston. This would save drilling holes in the barrel to install gas pistons and make gas operation simple and near to that of blowback operation.
It may or may not have the 1mm headspace as previously mentioned but angled lugs to ease extraction and reloading. It may also have a self cleaning bolt to remove residue inside the receiver and a fluted chamber.
To explain again, When firing, the bolt is in a fully locked position, the fully locked bolt moves backwards 1mm allowing the gas pressure to flood the chamber past the locking lugs. The gas pressure has to overcome the bolt carrier to unlock the bolt and reload.
Just to notify, this operation may vary (IE: rear locking lugs, internal locking piston, locking flaps etc)
It may or may not have the 1mm headspace as previously mentioned but angled lugs to ease extraction and reloading. It may also have a self cleaning bolt to remove residue inside the receiver and a fluted chamber.
To explain again, When firing, the bolt is in a fully locked position, the fully locked bolt moves backwards 1mm allowing the gas pressure to flood the chamber past the locking lugs. The gas pressure has to overcome the bolt carrier to unlock the bolt and reload.
Just to notify, this operation may vary (IE: rear locking lugs, internal locking piston, locking flaps etc)