The 7 cm Gebirgsgeschütz M 99 was a mountain gun used by Austria-Hungary during World War I. It was obsolete upon introduction as it had a bronze barrel, a spring-loaded spade to absorb the recoil forces and it had to be relaid after every shot. The high elevations required of mountain guns greatly complicated the provision of barrel recoil systems as the breech could recoil into the ground, and it would be some years before satisfactory systems were developed. These would result in the 7 cm Gebirgsgeschütz M 8 and M 9 that used the same barrel and ammunition as the M 99, but had Gun shields and more advanced recoil systems. These guns weighed 402 kilograms (886 lb) and 456 kilograms (1,005 lb) respectively, although the exact differences between them are unclear other than they broke down