The army tried to save money by using WC846/844 ball powder instesd of the IMR type powder that was really the proper propellant.Too much calcium carbonate in the ball powder clogged the gas tube.
“Too much calcium carbonate in the ball powder clogged the gas tube.”
That plus the brilliant minds of Robert McNamara’s Defense Department told the grunts that this was such a great rifle that it NEVER needed cleaning which is absolute nonsense with any mechanical device, especially in an uber-humid environment like Viet Nam.
We never had any problems with the gas tubes: it was the fouling in the chamber which caused the cartridge case to stick in place and then the bolt withdrew with enough force to tear the cartridge case head off.
Then the little sweetheart fed another cartridge into the old case and we had an unclearable mess. All while the enemy was shooting at you.
Fun stuff.