20MM Dummy


Once again, someone handed me this today and simply said, "You want this thing?"

I said yes!
The projectile is steel with a brass top.

Here’s a sketch of the headstamp. It appears to be something like an anvil in the center of the primer pocket with 2 small flash holes.

What can you experts tell me about this one?


This was made by AS Campbell Co. Inc., Boston MA in 1943.

The projectile should be painted dark brown.

As far as I know it is a standard drill round for training sailors on loading and firing of 20mm Oerlikon guns.


A bit more info - the 20mm Oerlikon became the standard light AA gun of the USN during WW2, effectively replacing the previously-fitted water-cooled .50 BMG. Some big ships carried large numbers of them by the end of the war.

The gun was also of course used by the RN throughout WW2 and stayed in service until well into the 1980s (at least). It only began to be replaced when the Falklands War demonstrated that it might be a good idea to buy some more modern AA guns…

The ammo is still made in several countries, so the guns must still be chugging away somewhere.


Chief…On my Navy ammunition display board from 1944, this cartridge is called “Cartridge, 20MM, Antiaircraft, (Navy) Drill, (Dummy)”. The entire projectile is painted brown.



Thanks gentlemen, you have confirmed what I thought to be the case, a round for the Oerlikon gun. The museum ship I volunteer on was covered with these in WWII and there is one on display. I am hoping I can get the museum to put this dummy (cartridge, not me) on display with the gun but I needed confirmation that it was the right round.

Tony, these Oerlikons were still in use by the USN into the mid-90s because I fired them on an auxillary ship (submarine tender) then. They were intended to defend against small craft, such as terroist or pirates, not aircraft, by that time. I have seen pictures, within the last few years of our cruisers and destroyers in the Persian Gulf with these on board too. Personally, I can only attest to the effectiveness of the DU rounds against a rather passive row of 55 gallon drums bobbling in the water at a few hundred yards.

Falcon mentioned the projectile of this round should be painted dark brown. Could someone post me a pic to see the color please? Painting would certainly help prevent rusting of the steel if its on display.

Some aircraft, such as the Navy’s Skyraider (post WWII) had 20mm guns in the wings. Were these Oerlikons and did they use the same round?



Here’s a pic of one with some brown paint left on it.

On the right is a WWII vintage version made by the Germans. Popular caliber with both sides of the conflict!

Per Tony’s “Flying Guns”, the Douglas AD Skyraider used the 20mm Hispano M3 cannon. That case is the 20x110mm with a regular (rather than rebated) rim and the same caliber ammunition that came in that ammo can you shared a picture of a while back.



Shotmeister - Were they definitely DU rounds fired from a 20mm Oerlikon gun? I was not aware that DU rounds in that calibre had ever been made.


No Falcon, I am not at all certain what rounds I was firing. I recall they were gray projectiles but only assumed, because of the time-frame, they were DU. Bad move on my part, especially on this site. Although they sent up quite a splash of water on impact, I don’t think they were any kind of explosive rounds.

Dave, thanks for the pictures and aircraft gun ID. I have been searching the web since making my earlier post and found some of Tony’s work which answered questions.

Thanks to everyone for the input.


Here are a couple of USN 20mm rounds. I know very little about them. As a Navy FT (Fire Control Technician) in the late 1950’s my job was to get the projectiles from the guns to the target and I didn’t have a whole lot of hands-on with the actual ammunition. Most of the 20mm’s had been removed from ships prior to my enlistment. With the exception of the gyroscope controlled gunsights, the shipboard 20’s were point, lead and shoot guns. I know nothing about the fire control arrangement of the aircraft guns.

Can anyone decipher the stamped and stenciled markings on the rounds?

  1. 20x110mm Mk.1 for the USN 20MM HS404. No headstamp. DURA = Dura Division of Detroit Harvester Corp., Toledo, Ohio. This round appears to have been partially chambered in the wrong gun.

  2. 20x110mmRB HE Mk.3 for the USN 20MM MK2 AAA. Headstamp = NOEN 133 1942 20MM-MK.2. NOEN = Navy Ordnance Engineering Laboratory, Dahlgren, Md.

The information I have for these rounds may or may not be correct!


Chief…We need Ray Meketa in on this…but…
Again, from the 1944 BuOrd board…

If, what you were firing was the Oerlikon, (20 x 110 RB) rounds with gray projectile are BL&P…

If, what you were firing was the later 20mm, (20 x 110) then a gray projectile is HE-I.
Of course all of this may have changed a bunch since 1944. !!..When I was in USN, we had the 20 x 110 guns (Not Oerlikon)(1971-1976)



Here’s a link to a 1947 reference on 20mm colors.


That first one you show has me very curious what that could’ve been shoved into to make it look like that. Perhaps done with a linking machine?



Didn’t we discuss the 20mm cartridges at some length not too long ago? Maybe before the Forum crashed? Someone (Rick) posted some colored photos from one of the sources. I had the same photo but can’t find it now.

This is from OP 911, 1943:


There are SIX types of ammunition as follows:

(A) High Explosive, with Tracer, projectile type “HL” loaded with Pentolite, an explosive formed by combining equal parts of TNT and PETN. Color of projectile-Blue.

(B) Same as (A) except projectile is loaded with Tetryl. Color of projectile-Light Grey.

© High Explosive, without Tracer, projectile type “HB” loaded with Pentolite. Color of projectile- Yellow.

(D) Same as © except projectile loaded with Tetryl. Color of projectile-White.

(E) Blind loaded with Tracer. Color of projectile-Dark Green Grey with 1/8" wide Yellow Band.

(F) Blind loaded and plugged. Color of projectile-Dark Green Grey.

NOTE-The above colorings apply to 20 mm. A.A. Ammunition only for Mark 4 and Mark 2. Do not confuse with colors used in other ammunition.


Dave & Ray

Thanks for the input. So that would make the round without a headstamp a MK 1 Ball for the Hispano-Suiza canon I quess, although I don’t see any color listed for that projectile.