List Of Tables
Table Page
I. 20-mm to 40-mm Cartridge Data 56
II. Abbreviations and Terms on French
20-mm to 40-mm Cartridges 1
III. Hispano-Suiza Projectile Types and Color Coding 145
IV. Oerlikon Projectile Types and Color Coding 146
V. NATO Ammunition Color Code 151
VI. Experimental US 30-mm Belted Cartridge Cases 154
VII. German Terms and Abbreviations Used on Ammunition or Packaging 160
Section I. INTRODUCTION
1. General a. This guide provides reference data on, and outlines procedures that will aid in the identification of, cartridges in the 20- to 40-mm range. It thus supplements Volume I, which deals with the identification of small-arms cartridges up to 15 mm; there are no service types of military cartridges between 15-mm and 20-mm. Much of the information that appears in Volume I is applicable in some degree to larger-caliber cartridges as well. Although the present volume provides information applicable to and adequate for the identification of cartridges in the 20- to 40-mm range, the reader will find it helpful to refer as well to Volume I.
b. Because of the proliferation within each country during the past 40 years of functional types, models, and color codes in many calibers of ammunition, the information in this guide is limited to cartridge designation and country and year of manufacture. Some guidance is provided as to the design and visual identification of functional types, but the determination of specific model designations or identification of color codes used by each country is outside the scope of this volume.
c. The term "cartridge identification" can encompass a wide span of activities, ranging from the simple determination of a cartridge's caliber and case length to a detailed examination that can include its country of origin, functional type, model or type designation, and even lot number, year, and place of manufacture. The problems involved in the identification of cartridges may be summarized in three questions, which this guide will help to answer:
(1) What is the cartridge designation? This is expressed by a brief descriptive designation that includes the projectile caliber and case length. This designation is applicable to all cartridges that can be fired in guns chambered for this specific cartridge.
(2) Who made the cartridge, and when? Normally this information can be derived from the markings that appear on the projectile, on the case wall, or on the cartridge base. If the cartridge is unmarked, or if the markings are for any reason inadequate, a detailed examination and comparison with similar cartridges of known origin may be necessary. Because of its technical complexity, such a comparison falls outside the scope of this guide.
(3) What is its functional type? More specifically, does the projectile contain an explosive charge that demands added caution in handling and storage? Frequently this can be determined beyond doubt from markings data, but if any question exists, an examination by technically qualified ammunition specialists will be necessary.
d. Ammunition in the 20- to 40-mm range is frequently termed automatic gun ammunition, since with very few exceptions all of the cartridges produced today in these calibers are designed to be fired in fully automatic weapons similar in operation to, but larger than, heavy machineguns. Cartridges in these calibers vary widely in design and performance, ranging from low-power cartridges that differ little from small-arms cartridges except in caliber and projectile construction to high-performance antitank (AT) and antiaircraft (AA) cartridges. Cartridges in the 20- to 40-mm range differ from small-arms cartridges principally in their use of artillery-type projectiles, frequently with an explosive charge, instead of the jacketed bullet construction typical of small-arms ammunition. In common with smaller-caliber cartridges, they almost invariably have a one-piece, drawn-metal cartridge case; the primer may be either a percussion primer of the type used in small-caliber cartridges or an artillery-type electric or percussion primer with a black-powder igniter charge.
e. Cartridges in this range originated with the 1-inch Gatling machinegun, introduced as early as 1866, which was followed by 1-pounder (approximately 37-mm) cartridges of several types, fired either from handpower-operated guns such as the Gardner, Nordenfeldt, and Hotchkiss systems or from single-shot, quick-firing guns. A self-powered automatic gun, the 37-mm Maxim, appeared as early as 1885. The term "pom-pom" was originally applied to this gun. Development since World War I has been directed primarily toward improved ammunition for automatic or power-operated guns for aircraft and antiaircraft use, with a reduced effort in the area of cartridges for semiautomatic weapons for accurate aimed fire against point targets.
f. Some of the cartridge types that are described in this guide were produced 40 or more years ago. Cartridges made during and even before World War II are not necessarilv unserviceable because of their age; if they have been stored under favorable conditions of low humidity and low-to-moderate temperature, and if the brass cartridge case has not become brittle from exposure to the mercuric compounds in the primer or from improper annealing of the metal, they may be safe to fire, though fuzes and tracers may not function reliably. Serviceability must be determined through inspection and testing by qualified ammunition socialists._____________
2. Organization
This guide comprises four major sections.
a. Section I outlines the scope of this guide and its organization. It also provides general information on construction, characteristics, and terminology of automatic gun ammunition that will aid in the use of this guide.
b. Section II provides instructions for the use of this guide in the identification of cartridges from dimensional and visual data.
c. Section III provides a series of outline drawings of cartridge cases, a tabulation of major cartridge dimensions, and a brief description of each cartridge type in terms of its origin, using weapons, principal countries of manufacture and use, and current status. Cross-reference of information in these three areas is aided by the use of an index number that is assigned to each cartridge designation.
d. Section IV presents representative cartridge identification data for each of the major countries that has produced ammunition in this caliber range.
3. Cartridge Cases
The primary feature in cartridge identification is the cartridge case. Its shape and dimensions, which must conform to the chamber size of the gun for which designed, indicate the type and probable military role of the weapon, which in turn may suggest the country of origin or the political polarity of the user. Key aspects of cartridge-case design and construction are outlined in the following subparagraphs.
a. The cartridge case (which, incidentally, can account for more than half the weight of the complete cartridge) provides a sturdy, reusable, weatherproof container that unites the primer, propellant, and projectile into a unit and protects them from damage in storage, handling, and loading or feeding. During firing, the case provides obturation, sealing the breech end of the barrel to prevent the escape of hot propellant gases into the gun mechanism. When automatic weapons are fired, the cartridge case serves an equally important purpose in acting as a heat sink: It extracts a significant portion of excess heat from the gun chamber after each shot, thus reducing the risk of overheating the gun and the attendant possibility of premature firing (cook-off).
b. To provide desired performance characteristics, military cartridge cases must be robust; all are of centerfire construction, with a reinforced cartridge case head and a centrally located primer that ignites the propellant contained in the cartridge case. Cartridge cases are made principally of brass or mild steel (either plated or lacquered), though in recent years aluminum cases have made a strong appearance. Cases are manufactured by punch and die operations, termed "drawing," with heat treatment to provide desired metallurgical characteristics.
c. Cartridge base types, which serve a functional purpose in the feeding, positioning for firing, and extraction of the fired case or the unfired cartridge, are valuable identifying features. For convenience in cartridge identification, the cartridge base description is used as an element in the descriptive designation of the cartridge. The five base types in use, with their abbreviations, are as follows: rimmed (R), rimless (no abbreviation), semirimmed (SR), belted (B), and rebated (RB). These types, which are shown in figure 1, are described in the following subparagraphs.
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