View Full Version : Help with ID of 20mm Round

January 5, 2010, 09:02 PM
Could anyone here help me identify this round? The band around the neck is marked as follows:

* 20-MM MK. 11-0A LOT [HMC] 1-16 *

I especially want to insure it is a Dummy/Inert round. Any help would be appreciated.


January 5, 2010, 09:11 PM
I have one like that but on the bottom of the shell there is an allen bolt that holds in the projectile.Just do what bug bunny gig and hit the bottom with a hammer and see what happens....:eek:

January 5, 2010, 09:21 PM
It appears to be a 20x110mm functioning dummy for one of several versions of 20mm cannon the US Navy used up through the 1970s; live rounds were produced in both percussion- and electrically-primed versions, but these all have a definite primer in the middle of the case-head, so yours is a dummy round, but with a filler so that it simulates the weight of a live round (something they used to test the feed systems on occasion); most dummy rounds in this calibre would look like the ones at http://www.gunbroker.com/auction/ViewItem.aspx?Item=147597018

January 5, 2010, 09:32 PM
Thanks for the info. The depth of knowledge possessed by forum members such as yourself never ceases to amaze me.

January 6, 2010, 04:57 PM
Inert, or "dummy" rounds are typically dual tone (bronze bullet/metallic case) but I have also seen the entire case/projectile in the same silver/metallic or bronze coloration.

The 20mm is electrically fired and has a electrical primer in the base of the cartridge.

Based upon what you have there, the case appears to be a dummy without the electrical primer installed.

It also looks like someone may have painted the projectile red to resemble a Phalanx round (see link below). Go to "medium caliber ammunition".


January 8, 2010, 01:30 AM
I thought all "dummy" inert ammo/projectiles were blue?????

January 8, 2010, 08:10 AM
I thought all "dummy" inert ammo/projectiles were blue?????

It may be, as Jager1 suspects, that it has been repainted. I will take a closer look at it to see if there are any signs of blue paint under the red.

Also, the projectile spins freely at the area where the band is attached. Should it do this?

B. Lahey
January 8, 2010, 03:42 PM
Not all nations use or have used the blue = inert color code. Red could mean the same thing or something different depending on where and when this was made.

The MK coding is Britishy / Naval. It could be English or from a former colony that still uses Britishy terms for ordinance. It may have come from HMC (Heavy Mechanical Complex), Pakistan, although I have not been able to find anything about 20mm ammo from that facility.

It could be for the Mk 11 HIPEG aircraft gun, although I have not found much info on that system. I found some passing references, so it existed, but other than that I dunno.

Here's a note of an Argentine 20mm round from 1974 with the similar markings, but there is no photo:

It may be an earlier 20x102mm round instead of 20x110mm.

Kind of sparse info, but one of those factoids may be the search-term you need to dig up more.:)