After reviewing the design of the AR-15, I always have a good chuckle to myself when I see "direct impingement vs gas piston". I doubt some people asking the question have any idea what really goes on.
The "direct impingement" design is a gas piston. The piston is inside the bolt carrier. The expanding gasses push the bolt forward, and the carrier to the rear. This relieves some of the pressure on the locking lugs during rotation of the bolt.
the "gas piston" design is, as mentioned above, and operating rod type piston. It just moves the interface between the hot expanding gasses and the mechanical reciprocating assembly from inside the receiver, to above the barrel.
If you are within a narrow set of parameters, the piston can be an advantage. Otherwise, I'll stick with DI.
The "direct impingement" design is a gas piston. The piston is inside the bolt carrier. The expanding gasses push the bolt forward, and the carrier to the rear. This relieves some of the pressure on the locking lugs during rotation of the bolt.
the "gas piston" design is, as mentioned above, and operating rod type piston. It just moves the interface between the hot expanding gasses and the mechanical reciprocating assembly from inside the receiver, to above the barrel.
If you are within a narrow set of parameters, the piston can be an advantage. Otherwise, I'll stick with DI.
