Regular Spanish troops were mostly armed with modern charger-loaded, 7mm 1893 Spanish Mauser rifles and using smokeless powder. The high-speed 7×57mm Mauser round was termed the "Spanish Hornet" by the Americans because of the supersonic crack as it passed overhead. Other irregular troops were armed with Remington Rolling Block rifles in .43 Spanish using smokeless powder and brass-jacketed bullets. U.S. regular infantry were armed with the .30–40 Krag–Jørgensen, a bolt-action rifle with a complex magazine. Both the U.S. regular cavalry and the volunteer cavalry used smokeless ammunition. In later battles, state volunteers used the .45–70 Springfield, a single-shot black powder rifle.