20 x 140 CTA questions


I have recently acquired an empty cartridge case, I believe of US origin, for 20 mm telescoped ammunition. The case is a grey metal cylinder 42.4 mm (1.67 inches) in diameter with a seam down its length. There are two end caps with holes for a screw-in primer and the projectile. The whole case including end caps is 140 mm (5.5 inches) long. The case is lightly magnetic, the end caps strongly so. There are no markings of any kind on it.

Can anyone provide me with any information about this? I am interested in the project which led to this being made, the gun it was designed for, when it was made and by whom, and how it performed.

Thanks for any help!


Tony, the 20x140 CTA was a Honeywell development from the 1980’s that was later carried on in the 1990’s for the Air Force 20 mm Advanced Gun Technology (AGT) intended for the future Advanced Tactical Fighter (ATF). Other companies were involved, like Aerojet, General Electric and Ares.

Please, could you post pictures?




Thanks Fede, photos below.

Do you know anything about the gun it was supposed to be fired in? A rotary of some kind I expect.


Tony, the case body seems to be made of stainless steel if it is less magnetic than the steel end caps.


Some information from the report: Evaluation Report, DOD Office of the Inspector General, DOD Cased Telescoped Ammunition and Gun Technology Program, 1996: dodig.mil/audit/reports/fy96/96-164.pdf

Diagram contained in the report.



Excellent! Thank you very much, Brian.


Am I right that the photo shows a few pin holes through the weld seam at one end of the case? Perhaps this case was a reject that failed quality control for that reason and never loaded?


Yes, you are right - there is a small hole in the seam near the mouth of the case.


A follow-up question: one US case-telescoped programme not mentioned in the list provided by Brian above is the 30 x 166 AMCAWS, which stands either for Army Materiel Command Automatic Weapons System or Advanced Medium Caliber Automatic Weapon System. The ammunition is described in Dale Davis’s excellent book on the development of US aircraft gun ammunition from the 1950s to the 1980s, although it was not intended for use in aircraft but in a relatively low-rate-of-fire army AFV gun.

One curious aspect of the case is that it is reverse-tapered (i.e. wider at the mouth 54.8 mm / 2.16" - than at the base - 51 mm / 2.0") for a front-loading gun system (presumably some form of revolver?). There’s a cheap (!) little book about the system here: http://www.amazon.co.uk/Mathematical-Advanced-Medium-Caliber-AMCAWS-30/dp/B00BGLRQHW but that would be too technical for my needs anyway - I would just like brief details of the ammo weights and performance (as in the table above) plus if possible some info about the gun. Can anyone help?

The stamp on the case side says:

AMC - 30mm C/C
Target Practice
Hercules Incorporated
(something) X01 - Aug. 1972


A low grade copy (PDF) of the report A Mathematical Model of the 30 MM Advanced Medium Caliber Weapon System (AMCAWS-30), 1977 is available (for FREE) here: dtic.mil/dtic/tr/fulltext/u2/a039713.pdf

AMCAWS 30= Advanced Medium Caliber Aircraft Weapons System 30mm

From the Abstract of the above listed report is this description-

The AMCAWS-3OMM weapon is currently under development in the Advanced Concepts Group, Aircraft and Air Defense Weapons Systems Directorate, General Thomas J. Rodman-Laboratory Rock Island, Ill. (SARRI-LW-A). AMCAWS is a 30 milimeter single barrel weapon that utilizes an aluminum cased, fully telescoped, and consolidated propellant round with ballistic characteristics slightly better than GAU-8 rounds. The prototype weapon fires ten round bursts at a nominal rate of 120 spm. The second prototype weapon has a nominal rate in excess of 400 spm,”

Army Research and Technology Laboratories Annual Report FY 77. dtic.mil/dtic/tr/fulltext/u2/a049212.pdf

Pages 23 - 24

Some technical info here: ROTATING BAND TORQUES AND STRESSES ON AMCAWS 30MM COPPER BANDED PROJECTILES, 1975. dtic.mil/dtic/tr/fulltext/u2/a012237.pdf

From the above listed report.



Thanks again, Brian, I don’t know how you’re able to find this stuff! My google doesn’t work half as hard ;-)

There seems to be a mismatch between Dale Davis’s description of the ammo - which states that the “stop mode” of operation was used (only suitable for a low rate of fire - as Davis says was intended of the army gun) and the statement in this report that it was intended to arm aircraft, which generally requires a high rate of fire.

Edit to add: ah right, a helicopter gun! Makes sense, but if the ammo is a shade more powerful than the GAU-8/A’s, the recoil would take some managing!