 Military surplus .303 British ammunition that may be available often has corrosive primers, given the mass manufacture of the cartridge predates Commonwealth adoption of non-corrosive primers concurrent with the adoption of 7.62 NATO in 1955.There is no problem with using ammunition loaded with corrosive primers, providing that the gun is thoroughly cleaned after use to remove the corrosive salts.The safe method for all shooters of military surplus ammunition is to assume the cartridge is corrosively primed unless certain otherwise.