elite_hunter_sh3 |
03-24-07 07:41 PM |
- 1965 - 1967. Field reports from Vietnam began to look much more pessimistic. M16 rifles, issued to US troops in the Vietnam, severely jammed in combat, resulting in numerous casualties. There were some causes for malfunction. First of all, during the introduction of the new rifle and its ammunition into the service, US Army replaced originally specified Dupont IMR powder with standard ball powder, used in 7.62x51mm NATO ammunition. The ball powder produced much more fouling, that quickly jammed the actions of the M16 unless the gun was cleared well and often. This pitifully combined with the fact that the initial M16 rifles were promoted by the Colt as "low maintenance", so, for the sake of economy, no cleaning supplies were procured for new M16 rifles, and no weapon care training was conducted fro the troops. As a result, soldiers did not knew how to clean their rifles, and had no provisions for cleaning, and thing soon turned bad. To add the trouble, the ball powders also had a different pressure curve, so they produced higher pressures at the gas port, giving the rise to the rate of fire, and, thus, decreasing accuracy and increasing parts wear.
- 1967 - 1970. The deficiencies discovered in previous years began do dissolve. 5.56mm ammunition was now loaded using different powders that produce much less residue in the gun action. The barrel, chamber and bolt of the rifles were chrome-lined to improve corrosion resistance. Cleaning kits were procured and issued to troops, and a special training programs were developed and conducted ever since. Earliest cleaning kits could be carried separate from rifle only, but since circa 1970 all M16A1 rifles were manufactured with the containment cavity in the buttstock, that held the cleaning kit. At the same time (circa 1970) the new 30 rounds magazines were introduced into service instead of the original 20 rounds ones, to equal Soviet and Chinese AK-47 assault rifles, which had 30-rounds magazines from the very beginning.
- 1977 - 1979. NATO trials lead to the adoption of the improved 5.56x45mm cartridge, developed in Belgium by FN. This cartridge, initially developed in conjunction with the FN Minimi light machine gun, featured a slightly heavier bullet with accordingly slightly lower muzzle velocity. The resulting long-range performance, however, improved due to the better ballistic coefficient of the new bullet. The SS109 required a faster rifling twist to stabilize its bullet, than the original 5.56x45mm US M193 ammunition. The M193 was used with barrels rifled with 1:12 twist (1 turn in 12 inches), and SS109 was preferred to be fired with 1:7 twist (1 turn in 7 inches). Some arms manufacturers preferred to make their guns with intermediate 1:9 rifling, which would be equally good (or bad) for both old and new loadings.
courtesy of
http://world.guns.ru/assault/as18-e.htm
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