I was sorting some 30-06 brass my Dad sent down, one of the head stamps is "W.R.A. CO. .30G 1906". I wonder how old this case is? He also sent down a Williams Gun Sight "Reloaders Cartridge Box" (Cardboard cartridge box) with load data from 1959.
Andy

The G stands for "Government", a distinction that was unnecessary for the military to make, and which nobody uses, now. I will guess this was from between the world wars, and is possibly as old as the 1920's, when sporterized surplus Springfield actions were getting popular and helping civilians distinguish the "government" .30 caliber from the then more familiar .30-30 might have been useful.

The "Government" designation may have also served to distinguish it from the "30 ARMY" (30-40 Krag) also?