A bayonet lug is a standard feature on most military muskets, rifles, and shotguns, and on some civilian longarms. It is intended for attaching a bayonet, which is typically a long spike or thrusting knife. The bayonet lug is the metal mount that either locks the bayonet onto the weapon or provides a base for the bayonet to rest against, so that when a bayonet thrust is made, the bayonet does not move or slip backwards. Less than 400 years ago, bayonet lugs or their predecessors that allowed them to slip over the barrel did not exist.