Bayonet lug

A bayonet lug is a standard feature on most military and on some civilian long guns.

Prior to the lug's invention, plug bayonets were used, which were shoved into the muzzle end from a tight-fitting stub, preventing the firearm from being reloaded or discharged.

This type of bayonet slides over the muzzle end with the blade offset to the side at a right angle, above or underneath the barrel.

[3] Bayonet lugs are usually located near the muzzle end of a long gun barrel.

[4] The lug is occasionally placed on top of the barrel, if serving as the base of the front sight, it is more often mounted to the side or bottom of the barrel.