The breach has a projectile retaining catch to prevent the shell sliding out at higher elevations before it is rammed with a manual rammer.
2.
The early versions of 18-pounder anti-aircraft guns remained in service, apparently only in the home defense of Britain . 35 were in service in Britain in June 1916 and 56 at the end of World War I . After the war, they were converted back to field gun use by removing the cartridge retaining catch.