Well to be fair in Vietnam the military sent our guys out with M16s and no cleaning kits. Told them the weapon didn’t need to be cleaned. Its totally does have to be maintained. Also at that time the military was using ammo with a different kind of powder than Stoner’s specs called for. There was some talk that they were even using WW11 powder.
Then the trick shoulda been to design a gun that used that ammo. Gigantic Duhh factor.