Found the reference.
Huon's Military Rifle and Machine Gun Cartridges indicates that in 1932 the ball N was adopted and had black, purple, our green primer annulus.
While he doesn't specifically say those colors were used only on ball N, the only mention of primer annulus colors is in reference to the ball N.
"The gift which I am sending you is called a dog, and is in fact the most precious and valuable possession of mankind" -Theodorus Gaza
Baby Jesus cries when the fat redneck doesn't have military-grade firepower.
Last edited by Mike Irwin; October 11, 2012 at 05:18 AM.