This is probably not the first time we’ve mentioned this article but, it’s a good read for those considering a new AR and debating the traditional direct impingement (DI) verses short and long-stroke piston designs available today. It’s written by Mike Pannone. Pannone’s opinions carry a good deal of weight with me. He opens thusly:
I fired 2400 rounds of M193 through a 14.5” M4-type upper receiver from Bravo Company Manufacturing (BCM) with no lubrication, and without any rifle-caused malfunctions. So; why can I get my direct impingement rifles to repeatedly do things that conventional wisdom says they can’t do?
The article was originally published in 2010 but, it applies today as much as it did then. I for one have not been bitten by the piston bug mainly because the would be engineer in me looks at piston driven ARs as a “retrofit” of an existing system that in my own experience runs just fine if built by a reputable builder/manufacturer and properly maintained by me. Pannone’s article is not a DI v. piston debate piece. In fact, it focuses on the M4 in its original DI format and straight-forward, simple solutioned Pannone has found allow the classic M4 to run well over 2000 with zero issues, even with little or no lubrication. You can read the article in its entirety here.