US 20x110RB Oerlikon drill round projectile colour

Last year I got a US made WW2 era 20x110RB Oerlikon drill round. It is the same style as the .50 BMG drill rounds, with three holes at 120 degrees to each other around the side of the case, no primer and an empty HE projectile with dummy fuze. The projectile was rusty when I got it, I have only recently properly cleaned the rust off it. Should the projectile be painted or left as bare steel? If it should be painted, what colour should it be?

Thanks in advance for any info.

In my time, post WWII, blue was the proper color for training ordnance and yellow for explosive. However, I can’t say this applied during WWII. I will check on the Yorktown next week and see if they have any 20mm rounds that I might confirm this with. DO NOT PAINT YOUR ROUND BASED ON THIS INFO!

This may sound “picky” at first, but you must define “training” before you choose a color code. IF you are talking “practice” then the light blue is correct. However, in a lot of ordnance, this color does NOT denote a completely INERT or dummy item. Many items; practice mines, mine fuzes, bombs and SOME ARTILLERY PROJECTILES can have explosives inside, even though they are painted blue. That charge invariably will be a smaller charge of a less lethal or less “brisant” mixture, merely to indicate functioning or to allow observation of the function; however, it is NOT INERT. Although it is normally acceptable to “assume” a blue painted 20mm PROJECTILE is INERT, ie. no explosive charge whatsoever. BUT to get into a habit of doing this is incorrect–the casing is still hazardous as it may have propellent, the projectile may have a tracer element, and you may lead someone to think that what is true for 20mm is true for example, 155mm, and that could be actually hazardous. It is best to stick with the “correct” answer, and BLUE projectile is practice, not “training.” Initial training is normally done with totally inert items, often called “dummy” and I have seen these in unpainted steel, a “galvanized” look, and painted black. Currently there is an anodized bronze color for 20mm “inert” rounds, in addition to the above colors, and a couple of shades of “off-white” plastic.
Just trying to keep us safe, not be critical, esp. as Shotmeister had fully qualified his statement, and warned us already!



WWII U.S.Navy 20mm Dummy/Drill cartridges for the MK 2, 3, and 4 had the drilled case, as you described, and the projectile was painted brown. After a lot of use the paint would be very worn and they appear to be unpainted (which I think many actually were).

Projectiles painted blue were HE/T.

Post WWII paint schemes were completely different for most USN Artillery ammunition.


Here, a picture of a 20mm Dummy/Drill Mk4 cartridges of my collection :


Thanks for the info. Painting it brown like that shouldn’t be alot of trouble.

Hey Falcon

Here’s a pic of my example. Looks to be akin to Maverick’s sample. To help confirm the color.

Thanks for the photo Rick.

Were the projectiles on these brazed into the case? Some of the brazing seems to have seeped onto the steel part of the projectile on my round, just above thedriving band.

Apparently so. Mine is solid but no obvious brazing residue.

I suppose it makes sense as there is no crimps, and in wartime they wouldn’t worry about a bit of brazing residue on the projectile.

I have two in my collection [on the left] One has a gray tip…is this ligit? And what are the two dummy [or inert] rounds in the middle and the empty cases on the right?


Stevef, the fired cases on the right are typical for fired 20x110 Oerlikon cases, since this cannon works like the world’s largest open-bolt submachinegun; the round is fired while it’s still being chambered, and the bolt is still moving forward, so the necks of the cases are blown out and forward. The middle two rounds appear to be another 20x110 round, the 20x110 Hispano-Suiza, which was used in a number of aircraft and anti-aircraft cannon until fairly recently (and may even still be in service).

Thanks for the info, the expanded necks really had me guessing! Is the gray tipped round original???