[Adam Helmer]

Mr 16 gauge,

Thanks for the trip down memory lane. I got my first M16 in July 1965 and we were told a few MYTHS:
1. The projectile goes so fast, no sight adjustments are needed after initial zero.
2. The powder burns so clean, no cleaning is necessary after firing.
3. This (.223) round is more powerful and devastating than the .308 in the M14.

As I understand it: Eugene Stoner developed the gun using IMR4475 powder and the first cartridges were so loaded. Along came Secretary of Defense Robert Strange McNamara, who learned the government had on hand huge stocks of Ball WC-846 powder for loading .308 ammo. Strange decreed the "existing stocks of powder on hand would be used to load .223 ammo" at government ammo plants.

The Ball WC-846 powder had a different burning rate and the pressure curve was further forward down the barrel and on the direct impingement gas system of the M16 and burned dirtier than the initial IMR powder. The cyclic rate of the M16 went up and the gung dumped on the bolt carrier and bolt was like tar. Rounds stuck in the M16 chambers, extractors tore through the case cannelure of fired rounds and GIs died in combat.

Finally a few things happened: GIs got cleaning kits, the powder type used in the ammo went back to designer Eugene Stoner's specs and McNamara faded away.

Adam