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 ?
For this reason, bullet-to-bore friction was very limited, which results in less pressure than would occur with a bullet that obturates more easily.
It allows the dentists to obturate the canals that are well oriented and the operator is familiar with better tactile sensation.
The aim of root canal treatment is to remove any remaining vital, apical tissue and the necrotic coronal portion of the pulp that might be sustaining the and stimulating the resorbing cells via their blood supply, and to disinfect and obturate the root canal system.3,4 The literature describes various obturation techniques which have been advocated by different authors to obturate internal resorption defects.
As you can imagine, accuracy was sub par and smokeless powder doesn't obturate the bullet enough to fill the grooves in the barrel.
He means "obturate" rather than "obdurate." It has been so many years since I trained at Fort Sill I had to look it up in the Book of Handgun Reloading.
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.
It's perfectly normal so see a little carbon blacking but when it's excessive like that we know that there wasn't even enough pressure to obturate the case at all.
The Foster slugs have very shallow rifling and since these slugs obturate in shotgun bores, most of these grooves are ironed out in the process.
Many of today's shooters have tried shooting these old rifles using hard alloys -- wheel weights and such -- and experienced dismal results when the .457-inch and even .459-inch bullets failed to expand properly and obturate the bore.
Maxillectomy to reconstruct or obturate? Results of a UK survey of oral and maxillofacial surgeons.
Three techniques have been suggested to obturate an immature tooth, which involved the use of a root filling material without the induction of apical closure.
A poly-bore-barrel will take less propellant to get the same velocity, because the bullet obturates more fully (fits the bore), and some (me for one) have found ultimately there's a little additional speed available.