BREECH LOCK - CARTRIDGE CASE TYPES

THIS 62 PAGE BOOKLET CONTAINES OVER 100 PHOTOS AND INCLUDES SEVERAL PAGES OF PATENTS / APPLICATIONS. ALL INCLUSIVE IS A HISTORY, CLASSIFICATION OF VARIOUS PATTERNS AND GENERAL SPECIFICATIONS.

THE AUTHOR

KIJIRO NAMBU

NAMBU MACHINE PISTOLS

THE AUTHOR

KIJIRO NAMBU

NAMBU MACHINE PISTOLS

ARTICLES

AIR CRAFT WEAPONS

From some 230 BIBLIOGRAPHICAL REFERENCES,

this literary work is composed of

542 PAGES with

686 ILLUSTRATIONS, including patent drawings and descriptions.

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THIS 62 PAGE BOOKLET CONTAINES OVER 100 PHOTOS AND INCLUDES SEVERAL PAGES OF PATENTS / APPLICATIONS. ALL INCLUSIVE IS A HISTORY, CLASSIFICATION OF VARIOUS PATTERNS AND GENERAL SPECIFICATIONS.

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DEFINITIONS
BREECH LOCK - CARTRIDGE CASE TYPES

BREECH LOCK
The mechanism which locks the breechblock into battery position.

BULLPUP [design]
A weapon, short in barrel and mechanism, in which the action assembly and/or cartridge magazine is located behind the trigger.

BUFFER
A resilient object located at the rear end of an automatic weapon’s recoil mechanism, which cushions the bolt in its rearward motion and generally prevents ‘shock’ recoiling of the action. The object may take the form of soft material, spring[s] or an air compression chamber all to provide smooth movement during recoil. Spring buffers can be so designed to assist in the speed of bolt return to its full forward position to increase the rate of fire. Additional resilience material can also be used to decrease the rate of fire.

CALIBER/CARTRIDGE DESIGNATIONS [metric]
Metric designation is in millimeters and indicate bore diameter and length of cartridge case. Example as the Japanese Arisaka cartridge, 6.5x50mm indicating the diameter as 6.5mm and the cartridge case length as 50mm. The designation may be followed by letters: R [rimmed], SR [semi rimmed].

CARTRIDGE CASE TYPES
For our purposes, cartridge cases are classified into 3 types. Rimmed, semi-rimless, rimless.
Rimmed. This type of cartridge has a protruding rim at the base which is several diameters larger than the case at its junction. The primary purpose is to serve as a shoulder for the extractor to rest against and “grip” for the cartridge removal from the chamber after firing. An example is the British .303 caliber ammunition.

Semi-rimless. This type of casing provides a cannelure, [extractor groove], around the base of the case allowing the extractor to grip the exposed rim base lowering extractor protrusion interference. The diameter of the base however is smaller than in front of the cannelure but larger than the rimless cartridge. The Japanese Type 92 heavy machine gun is designed to fire either their semi-rimmed or rimless 7.7 mm cartridge.

Rimless. The casing has a rim at the base with a cannelure at the junction of the rim for the entire circumference of the case. The rim generally has the same diameter or smaller than the case at its junction. Most modern small arms utilize the rimless cartridge case.