obturation

The act of closing or stopping up, or the state or condition of being obstructed or closed.

Specifically, in gunnery, the act of closing a hole, joint, or cavity so as to prevent the flow of gas through it: as, the obturation of a vent, or of a powder-chamber. See fermeture, gas-check, obturator.

The act of stopping up, or closing, an opening.

The act of stopping up, or closing, an opening.

The process of a bullet expanding under pressure to fit the bore of the firearm, or a cartridge case expanding under pressure to seal the chamber.