30x173 GAU-8/a and GAU-9/A

Can any one provide me with a list of the load types for the GAU-8/A (Percussion Primed) and GAU-9/A (Electric Primed) rounds including the case and projectile colors. Also, proper designation. I know the PGU-13 A/B is HEI, PGU-14 B/B is API, PGU-15 /B is TP and PGU-16 /A is Durible Dummy. Are there others? What do the A/B, B/B, etc. mean? I remember reading somewhere that the width, number and color of the driving bands has special meaning. What are they. I have all blue projectiles with no driving bands (TP), yellow projectile with 1 wide red plastic driving band and gold dummy with 2 narrow white bands. I have red, gold, greenish-gray and olive-drab cases and have seen blue. Any others?

There are also red an purple ones.

I was under the impression that the width and number of driving bands was just a variation between manufacturers. Looking at the web sites for ATK and General Dynamics, the ATK page shows 30x173 cartridges with a single wide driving band, while the General Dynamics page shows double narrow driving bands.

ATK’s medium caliber ammunition page:

General Dynamics’ medium caliber ammunition page, 30x173mm section:

The ATK page shows a few other variants in 30x173 for the Marine EVF Bushmaster II cannon, although they don’t use the PGU designation.

It looks like ATK uses the driving band color as part of the projectile identification. Their PGU-13/B HEI has a yellow projectile with red driving band, while the General Dynamics round has a yellow projectile with a red band painted at the top. Similarly, the ATK PGU-14A/B is black with a red driving band, while the GD projectile is black with a red nose.

As far as the meanings of A/B: the letter before the slash is the model (A is the first model, B is the second model, etc.) and the letter after the slash indicates the installation of the item - B being “Aircraft installed - must be expended on mission”. If you have back issues of the IAA journal, there’s an article by R. E. Leiendecker starting on page 3 of journal 323 that discusses the Air Force designation system.

Regarding case colors, in addition to the ones you and EOD mentioned, I have a couple of PGU-16 dummy rounds with black anodized cases (gold projectiles, double tan driving bands).

Chip–Thank you for the links. The ATK link is especially good. It will answer many of my questions for the correct terminology for 20mm and 30mm rounds.

I appreciate the other explanations of some of my questions. Are the case colors tied to the maker or are they color coded to the load type or what?

I don’t know if the case color has any significance. It seems plausible that the gold case on the PGU-16 Dummy would be for identification purposes but that’s just a guess.

I only have a few of these rounds in my collection, but tonight when I get home I’ll see if there are any trends as far as specific case manufacturers using specific colors.

Chip–I only have 4 30x173 rounds. 3 of them are GAU-8/A (percussion primed) and 1 GAU-9/A (electric primed). Here are the details so you can compare against yours:

#1 GAU-8/A. Red empty case. Made by USE (Piper Industries). It has an inked “A” on the head (any idea what that means?).

#2 GAU-8/A. Olive-Drab case. HEI (INERT stamped on projectile). Aluminium nose cap, all yellow projectile, 8mm wide red plastic driving band. Made by ACN (Amron Corporation)

#3 GAU-8/A. Orange-Gold case. PGU-16/A Durible Dummy. All gold projectile with 2 white 5mm wide driving bands. Made by AOMC ADJ (Aerojet Ordnance Mfg. Company).

#4 GAU-9/A. Greenish-gray case. This case is lacquered aluminium, not anodized. Dummy. All blue TP projectile. Made by RNO (Amron, Division Gulf + Western Systems, Waukesha, WI 53186)

Note the two different codes, ACN & RNO, for what appears to be two different divisions of Amron.

Based on the cartridges/cases I have, there seems to be a decent correlation between case color and manufacturer. My Amron (ACN) cases are all dark greenish gray, while my Piper Industries (USE) cases are more olive green. It’s hard to tell in the photos below, but the USE cases (second photo) are greener than the ACN cases (first photo).

My GAU-9/A round is the same as yours and is not pictured here.

Does your red Piper Industries case have a date on it? Perhaps they switched colors over the years, or perhaps the red case signifies something special. I don’t know the meaning of the “A” on the head.

Dark greenish gray cases made by ACN (Amron), projectiles have 2 7mm white driving bands:
1: Inert-loaded PGU-14B/B API, case made August 1991, cartridge loaded by unknown manufacturer.
2: Inert-loaded PGU-15/B TP, case made August 1991, cartridge loaded by unknown manufacturer.
3: PGU-15/B TP (no powder or primer), case made March 1982, cartridge loaded by unknown manufacturer.
4: PGU-15/B TP, case made June 1992, cartridge loaded by AJD (Aerojet, Downey CA) July 1992.
5: Fired case, PGU-13/B HEI, case made March 1980, cartridge loaded by AJD June 1980.

(Photo showing items 1-5 from left to right)

Olive green cases - the first two cases are made by USE (Piper Industries), while the last is missing the case manufacturer information. All projectiles have 1 17mm translucent driving band:
6: PGU-16/B Dummy, case made January 1981, cartridge loaded by MHR (Honeywell, Brooklyn Park MN) August 1981.
7: Fired case, PGU-15/B TP, case made October 1984, cartridge loaded by HJA (Honeywell, Joliet IL) February 1985.
8: PGU-16/B Dummy, cartridge loaded by MHR September 1978.

(Photo showing items 6-8 from left to right)

Dark gray (almost black) cases - both are PGU-16/A Dummy rounds loaded by AJD. Both have 2 7mm tan driving bands:
9: Case made by ACN 1978, cartridge loaded 1978. (Case is much darker than ACN cases in group 1.)
10: Case manufacturer unknown (stamp is worn off), cartridge loaded 1977.

Various colors with 2 7mm white driving bands:
11: PGU-16/A Dummy, orange case made by MMT (Harvey Aluminum Inc., Martin Marietta Aluminum Division) 1975, cartridge loaded by AJD 1975.
12: PGU-15/B TP, purple case made by IVI (Valcarter Industries) 1975, cartridge loaded by AJD 1976.

(Photo showing items 9-12 from left to right)

Ron - I just dug out a 30x113 dummy that has a red aluminum case made by Piper Industries (USE) in July 1977, round assembled by Honeywell (MHR) in February 1978.

I wish I had access to a large sample of Piper cases to see if there’s a cutoff date when they switched colors, or if they were making different colored cases at the same time!

In response to the question of whether the case color serves any identification purpose:

I just read a manual from Honeywell that outlines EOD procedures for 30mm GAU-8 Air-to-Air HEI cartridges (I believe this is an experimental round, and not the normal PGU-13 HEI). The manual indicates that the cartridge cases are coded according to FED-STD-595:

Blue (35190 to 35109) - Norris Industries (NOR)
Red (31158 to 31136) - Piper Industries (USE)

The numbers are color codes made up by the government (originally in 1956 and revised periodically since then) so that they could accurately communicate color specifications for equipment… You can type those numbers in at this web site and see the colors:


The manual wasn’t clear about whether the color coding was a government requirement or an internal requirement, but at least in this instance the case color was used for ID.

It would make a pretty dry journal article, but I may have to go out to the Woodin Lab and compile a list of case colors by manufacturer to see if any other trends emerge!