Encyclopedia · Fuzes, primers, and ignition

Cannon vents and vent pieces

The vent was the small channel through which fire reached the charge to fire the gun. A vent piece was a replaceable metal insert that let a worn vent be renewed.

Also known as: vent, vent piece, touchhole.

VentThe channel from the exterior to the powder chamber
FiringThe primer's flame passes through it to the charge
Vent pieceA replaceable copper insert to renew a worn vent

Firing the charge

The vent, or touchhole, was the narrow channel bored from the outside of the breech into the powder chamber. Through it the flame of a primer, quill, or portfire passed to fire the charge, and it was the point at which the gun was primed and fired.

Repeated firing eroded the vent, and to avoid condemning a whole gun for a worn vent, many were fitted with a vent piece, a replaceable insert of copper or a copper alloy, that could be renewed when it wore.

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