"The use of ball gunpowder left a very sticky residue in the barrel and the gas tube of the M16. Since the barrel wasn't chrome-plated and no cleaning equipment and/or lubricants were available, it hardened quickly and soon made the rifle inoperable. The residue also caused spent casings to become stuck in the chamber and the rifle suffered a rim shear extraction failure, where the bolt's extractor tore off a portion of the end of the spent casing, leaving the rest of the case stuck in the chamber. Because of the ball gunpowder's ballistic characteristics and the rifle's buffer's light weight, the M16 fired fully automatically with a cyclic rate of between 850-1000 rounds per minute, well in excess of the normal 750-850 rounds per minute. Compounding this comedy of errors was the lack of training and instruction given to those troops who were issued the M16."
-- The M16 in Viet Nam.
The development of the M16 is a good story to read re: the dangers of project
management, and matching design and implementation specs. Just imagine the
horror of going into battle with a weapon that fails completely with use.