extractor groove

extractor groove

[ik′strak·tər ‚grüv]
(ordnance)
Groove machined in the base of a cartridge case, a short distance above the head, which receives the extractor of the breech mechanism and permits the case to be withdrawn by the extractor; used in automatic weapons, in preference to extractor rims (flanges) formed on the cartridge case base.
References in periodicals archive ?
Just behind the extractor hook is a pad on the extractor body that positions it and determines contact of the extractor groove with the cartridge.
The semi-rim rests in the extractor groove of the underlying round, and in order to move the top round forward, it has to push all the underlying rounds deeper into the magazine under all that magazine spring pressure.
Cases can be formed from the .32 Long by removing the rim, cutting an extractor groove and sizing and trimming.
All feeding must be from the magazine and the extractor claw rides in the case's extractor groove starting at the time the cartridge moves upward out of the magazine.
Rim diameter is 0.407 inch and case body ahead of the extractor groove is 0.375 inch.
4 rimless cartridge requires small pawls to reach into the extractor groove remove the case.
Keep an eye out for that telltale bright, shiny ring in front of the extractor groove that indicates an incipient head separation.
According to NAA, "Behind the neck, all case dimensions and configurations, including the extractor groove, rimless case, cartridge diameter and bolt-face engagement are identical to the .380 ACP.
Check cases for any flaws such as a too-battered extractor groove and discard any that don't look right.
The Groove Smooth is located on the outside of the Chambered Reference and is used to identify the cylindrical runout of the re-sized brass and the trueness of the extractor groove, and also to ensure the groove is free of any defects or obstructions.