Now this is something that I did not expect to see make a technical comeback with the focus of modern firearms on rotating bolts. The new Alexander Arms .338 Lapua Magnum rifle (the “Ulfberht”) utilizes a flapper-locking bolt design. The base design was first patented in the late 1800’s (1870) by a Swede named Friberg

Similar in concept to the roller-lock designs that typified mid-century H&K’s, the flapper locking mechanism uses flaps attached to the bolt to retard the bolt’s rearward movement giving time for the powder to burn and safely unlock the firearm.

For those looking to understand how a flapper-locked firearm works, our own Ian from Forgotten Weapons has a great video showing the field strip of a flapper-locked German rifle.