Acronym-etymologies

[Dave Wilton]

>P.S. The US Army has what is almost a secret language for referring to
>firearms.

>"gun" is used only for artillery, except in the phrases "machine
>gun","submachine gun", and "Gatling gun".  (Darned if I know what a
>"submachine" might be---ask a man who wears dolphins).  Calling a rifle a
>"gun" is good for at least a give-me-ten.

Does anyone know any official sources for definitions of US Army/military
terms?

I know of the following which are good for many terms, but they omit really
basic ones like "rifle," "cannon," "machinegun," "pistol," and "tank."

AR 310-25, Dictionary of United States Army Terms
AR 310-50, Authorized Abbreviations, Brevity Codes, and Acronyms
FM 101-5-1, Operational Terms and Graphics
JP 1-02, DoD Dictionary of Military and Associated Terms

This last does have a definition for "gun," which is:
1. A cannon with relatively long barrel, operating with relatively low angle
of fire, and having a high muzzle velocity.
2. A cannon with tube length 30 calibers or more.

A gun is also distinct from a "howitzer," which is:
1. A cannon that combines certain characteristics of guns and mortars. The
howitzer delivers projectiles with medium velocities, either by low or high
trajectories.
2. Normally a cannon with a tube length of 20 to 30 calibers; however, the
tube length can exceed 30 calibers and still be considered a howitzer when
the high angle fire zoning solution permits range overlap between charges.

Most of the "self-propelled guns" are officially "self-propelled howitzers"
(or actually, "howitzers, self-propelled" and you pronounce it as "howitzers
comma self-propelled"). Despite the official definition, in everyday
parlance, we called our howitzers "guns."

There are lots of websites that give various definitions, but I can't find
anything official other than the above sources.