What a disaster. No wonder so many Americans were killed in an Illegal unjust war. My father being one.No .22 caliber cleaning kits were issued until 1967. M14 rods would not go through the bore. Chamber brushes were nonexistent in 1965, 1966, and 1967; still in short supply in 1968. Bore solvent issued didn't remove crud within the bolt carrier bolt socket. Didn't remove copper fouling either, so bullets were tumbling from the muzzle on in high round count rifles. Lubricant issued didn't adhere to surfaces in the hot, humid climate.
GI's were oiling cartridges to assure extraction from pitted chambers, which penetrated to the propellant. Broken extractors and extractor springs were an epidemic because there were no spare parts in country. GI's did not clean their magazines, which were biological breeding factories. Were loading 21 rounds in magazines. Didn't clean their weapons regularly because everyone knows aluminum doesn't rust.
DuPont propellant (IMR 820 did not deliver the specified 3,250 fps velocity at acceptable chamber pressures from the second powder lot on. Western ball propellant (WC 844) delivered the specified velocity only in some lots. Slightly slower WC 846 reliably delivered specified velocity, but increased gas port pressure (which had never been specified by either ArmaLite or Colt). Ball powders used were all made from recycled WW II naval propellant stocks and had far too much calcium carbonate (to stem chemical deterioration which was already well underway) which seized up the bolt in the bolt carrier. Hercules flake powders blew up guns on an irregular, but frequent basis.
Whiz Kid McNamara and his military yes men screwed this rifle roll out, right from the start.