Principles of automatic and semi-automatic firearms

dZ

New member
http://rkba.org/guns/principles/

Disclaimer: The following is provided for informational purposes only. The information here is derived from open sources. In the U.S. there is nothing
inherently illegal or controlled about this information. This document discusses general principles and not specific construction details. It is not intended to
be a construction guide, but an overview of general concepts. Do not attempt to construct firearms even if you are a) a skilled machinist, b) thoroughly
familiar with engineering issues such as strength of materials and metal finishes, c) capable of stress, strain and failure analyses, d) fully competent in
developmental safety issues, etc. By proceeding you agree that you are completely responsible for your actions. If you do not agree, do not proceed
further.

Introduction

This document provides a descriptive outline of the principles of automatic and semi-automatic firearms. It's derived mainly from Principles of Firearms by
Charles Balleisen, a relatively brief engineering book published towards the end of World War II in 1945 by John Wiley and Sons of New York and Chapman
and Hall Limited of London. Then a Major in the US Army Ordnance Department, Balleisen applied mechanical engineering principles to analyze firearms
designs through the end of the war. Balleisen sought to educate his wartime audience towards a sound, well-versed engineering approach to arms design.
Based on open literature of the time he included work from French, German and U.S. sources. He also included analyses of a few key contemporary arms.
His book is likely long out of print. I found a copy in my university's engineering library.

Due to typesetting complexity I have not included Balliesen's formulas and sample calculations in this document. Since his work is no longer available I may
attempt to rectify this later. Until then for a formal treatment of this subject, including background, theory and formulas, please see the recent (1997)
Brassey's Essential Guide to Military Small Arms: Design Principles and Operating Methods. It is of similar scope to Balliesen's work, but is broadened to
include a greater variety of designs, particularly those from Slavic countries, and more detailed analyses. This Brassey's title is available at amazon.com
and also at Barnes and Noble. I've just received and begun to review my copy. From this early sampling, I can strongly recommend it to any student of small
arms design.

There are many types of firearms, from muzzle-loading muskets, through bolt-action rifles, to magazine-fed semiautomatic rifles, to belt-fed machine guns,
slide-action shotguns, revolvers, pistols, etc. At their inception almost all were designed as state of the art military weapons. While hunting and recreational
uses of firearms are popular, most common small arms designs were originally military designs and many continue to have military use.

Since bolt-action rifles, revolvers, slide (pump) action shotguns, and so forth operate on different principles from automatic and semiautomatic firearms,
they are not included in this discussion. However, many of the basic functions and issues other than the operating system are similar or identical across all
firearms.

Note that this document does not attempt to catalog all instances of firearms. Some titles of such can be found in the Bibliography. Rather the goal is to
describe the fundamental definitions, functions and operating principles of automatic and semi-automatic firearms. In order to do so a few key examples of
existing arms are examined throughout the document. Some of the history surrounding their development is also discussed.

Principles of Firearms

A general description of the components, functions and operating principles of automatic and semi-automatic firearms.

1.Introduction
2.Definitions
1.General
2.Gun Types
3.Ammunition Components
4.Gun Components
5.Feed Components
6.Miscellaneous
3.Functions
1.Feeding
2.Obturating (Locking)
3.Firing
4.Extracting
5.Ejecting
6.Cocking
4.Operating Systems
1.Inertia (Blowback)
2.Delayed Inertia (Delayed Blowback)
3.Short Recoil
4.Long Recoil
5.Gas
6.Gatling
7.Chain
5.Bibliography

None of the information in these pages is controlled or restricted in the United States.



This document was prepared in protest of the arbitrary and politically-motivated executive order by President Clinton on April 6, 1998 to ban importation of certain semi-automatic firearms
which have been inaccurately labelled "assault weapons." True assault rifles are fully automatic military machine guns, not semi-automatic rifles. Importation of these firearms had
previously been permitted under earlier restrictions since they met the cosmetic and functional criteria defined by the Department of The Treasury's Bureau of Alcohol, Tobacco and
Firearms.

Since semi-automatic rifles have clear value as constitutionally-protected militia arms and are used in less than 1% of crimes, the order is misguided, ineffective, and will be found
unconstitutional. It's worth noting that this ban is an continuation of one begun by President George H. W. Bush in 1989, then expanded in November 1997 by Clinton once again before the
most recent encroachment. None of these unilateral bans have been subjected to significant legislative or judicial review. Gun bans cannot reduce crime since according to the Federal
Department of Justice 93+% of felons get their guns illegally.

The only concrete guarantee of freedom is that the means of defense of our liberty is broadly distributed among everyday people. The means of force should not be concentrated solely
in the hands of an increasingly powerful and intrusive central government. Governments, even the best conceived, by definition exist in opposition to individual liberty. Check out Thomas
Jefferson, James Madison, Thomas Paine, John Locke....
 
Good info. I'm not sure "Rifle" is the right forum, but I'll leave it here for now. Might move it to "General", later.

Art
 
dz:

Interesting discussion, especially the references to Clinton and G.H.W. Bush, and their ridiculous, anti gun/anti civil rights executive orders. I make mention of CIVIL RIGHTS because the right to arms is a basic civil right.

As to the technical/engineering reference, I'm certain that for some people they would be most welcome, and otherwise interesting.
 
I don't quite get it. Is it a plug for a book, or a political discussion, or a discussion of firearms functioning? The topics covered in the TOC seem to be standard stuff, well covered in other books. The thoughts about rights are fine, but how do they tie in with the book?

BTW, obturation is not locking. It is the expansion of the cartridge case (or other type of breech seal) to seal off the powder gas from the breech. It takes place when the round is fired, not before.

Jim
 
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