extractor groove

Next the rims, extractor grooves, and flash holes are cut into the case.

Cases are rimless and have an extractor groove.

In metallic cases, this ability is provided by a rim or extractor groove machined into the rear of the case.

The case has a thin rim and deep extractor groove in comparison to most rimless pistol cartridges.

Some large rimless magnum or military cartridges have a belt formed above the extractor groove.

For rimless cases, an extractor groove in the ammunition may serve as the point from which the extractor works.

This system uses sprockets and extractor grooves to feed, load, fire, extract, and eject rounds.

A recessed extractor groove allows an extractor to grab the cartridge reliably.

A horizontal ring of small holes above the extractor grooves differentiated the Werkzeug round from the sS ball cartridge.

On a rimless case, the rim is the same diameter as the base of the case; it is known as an extractor groove.

The rim of the shell casing had a slightly larger circumference than the base of the cartridge and an extractor groove was cut directly above it.

Some very early blowback pistols used ammunition with no rim or extractor groove on the cartridge cases (e.g., 5mm Bergmann), and such pistols therefore lacked extractors.

The term belted magnum refers to any caliber cartridge, generally rifles, using a shell casing with a pronounced "belt" around its base that continues 2-4mm past the extractor groove.

The cartridge is said to be rimless if the extractor groove is machined into the body of the case so the rim is the same diameter as the adjacent part of the case.

In practice, many people call them "rimless" although that is something of a misnomer, because a true rimless case has the rim diameter the same as the case wall diameter just forward of the extractor groove.

The purpose of the "belt" on belted cases (often referred to as belted magnums) is to provide headspacing; the extractor groove is cut into the belt just as it is cut into the case head on a rimless case.

Since there is no rim projecting past the edge of the case, the cartridge must headspace on the case neck, for a straight walled case, or on the shoulder of the case for a bottlenecked case; the extractor groove serves only for extraction.

The shell casing head was spaced on this small rim; however, the utilization of the rim in this design complicated the mechanics of the cartridge because the rim would sometimes get hung up on the extractor groove of the cartridge while still in the magazine.