Self-opening and self-locking shotgun bolting systems and their relation to the old Morse taper.

by Sergey Lyalko

A machine taper secures machine tool spindles, with the taper fitting inside a like-angled socket. Old mechanical Morse principle, a self-holding variety of taper, helps in understanding failures of the shotgun bolting systems and their repair.

The evolution of muzzleloading firearms into breech loaders created a new challenge for the gun makers: the design of a strong Breech Bolting System (BBS). This mechanical portion of the gun ensures a tight breech seal for the duration of the shot. The bolting system takes a hard beating on every shot since the pressure in the chamber is trying to open the breech. This is universally true for any firearm and any bolting system but the subject of this article is a BBS of the break-open shotgun.

Right after the first appearance of the break-open design of…

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