LC is the stamp for Lake City Army Ammunition Plant.
Lake City is government owned but they contract production to ammo companies.
Lake City was operated by Remington from 1941 until 1985, at which point Olin (Winchester) took over.
The factory is near Independence Missouri.
The "67" is the year the ammo was manufactured.
The "NM" indicates the ammo was National Match grade, commonly used by military match shooters, and snipers.
If you shot the National Match in Camp Perry years ago, you were issued NM ammo for the M14 rifle or civilian M1A.