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case, a short distance above the head, which receives the extractor of the breech mechanism and permits the case to be withdrawn by the extractor; used in automatic weapons, in preference to extractor rims (flanges) formed on the cartridge case base.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 ?
If any resistance is felt, there's either a defect in the extractor groove and/or the cylindrical runout of the round.
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.
Whereas chamber support of a rimless centerfire cartridge in an AR-15 barrel terminates a bit forward of its extractor groove, the chamber of the F17-L fully supports a .
4 rimless cartridge requires small pawls to reach into the extractor groove remove the case.
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 .
This time I examined it to find bright spots around the case head about 1/8" ahead of the extractor groove.
Revolver cartridges have rims which are of a larger diameter than the cartridge case while semiautomatic cartridges are "rimless" with the rim normally the same diameter as the cartridge case itself necessitating an extractor groove be cut in front of the rim for the extractor to grab.
A possibility was that the pickup rail picked the cartridge up at the extractor groove rather than the rim.