Obturation

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obturation

[‚äb·tə′rā·shən]
(medicine)
The closing of an opening or passage.
A form of intestinal obstruction in which the lumen is occupied by its normal contents or by foreign bodies.
(ordnance)
Sealing of the breech of a gun to prevent escape of propellant gases in firing.

Obturation

 

the sealing of the barrel when firing a firearm in order to prevent the forward or backward escape of powder gases.

In guns that load by cartridge, obturation is achieved by the use of a brass cartridge case that expands when the gun is fired and ensures that the barrel is sealed on the breech side. In artillery guns that are loaded separately, obturation is achieved by using special devices in the breech called obturators. Escape of the gases in the direction of shell movement is prevented by the rotary bands of shells and casings of bullets; in mortars it is prevented by annular grooves on the cylindrical part of the shell.

References in periodicals archive ?
45 Colt bullet was accurate and pleasant but did not obturate the case enough to seal the chamber.
As you can imagine, accuracy was sub par and smokeless powder doesn't obturate the bullet enough to fill the grooves in the barrel.
Yes, they can help develop efficient patterns but they can give you fits in coming up with a wad column that will squeeze through the constriction of the choke, not be cut or deformed and still obturate in the larger bore.