The Big M4 Myth

Here’s my question for those that subscribe to the direct impingement fouling concept:
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?

This article is not a direct impingement vs. piston driven operating system debate and does not discuss piston guns at all. It is specifically dealing with a 14.5”AR-15 upper receiver with .062” gas port that’s as close to a Mil-Spec M4/M4A1 upper as I could find on the civilian market.

All I have ever asked and required of myself (and others) as a professional is that everything I say or write must be capable of being substantiated. I am asking some questions and giving my opinions, observations, and conclusions based on my own experience and testing.

For years I have been told, and heard others repeat, incessantly, that the direct-gas-impingement M16/M4 family of weapons is flawed because they deposit gas and powder residue in the upper receiver, and thereby are inherently unreliable with hard use. That sounds good in theory. However, in practice, I have not seen nor experienced it with my guns as a special operations soldier or civilian instructor. Why is that? Why don’t I have said commonly referred-to fouling problem with even excessive use and minimum maintenance?

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