Naval Antiaircraft Ammo & Weapon Systems

Here is a interesting item I picked up a few years ago. According to the manual, photos and box, it is a gyroscopic gun site for the US Navy 20 MM and or 40 MM Antiaircraft guns. It is in spectacular condition and came with a 2 instruction manuals and a technical manual. The cool thing is the way the oporater manual was written. It was writen so a child cold understand. Very simple, to the point with great associated visual diagrams or photos. I took a few pics. I am sure a few of our members have actualy fired these weapons while using this site. Hope it is not concidered off subject?

Man, you’ve got some of the coolest stuff.


There are lots of great 20 and 40mm cartridges to collect. Both of these guns were used by BOTH sides in WW2 so you can find production in Allied and Axis countries. The rarest of all is the 40mm Bofors made by Japan.

Give these guys a break and show them some of the REAL INTERESTING stuff which you have roaming around the back yard and/or living room !

Haha! I should take some pics of the “Roaming Stuff” in my back yard. I doubt the forum folks will concider a tiger ammo :-)

I would love to see a photo of the rare Japanese 40 MM. I did not know that so many countries utilized this weapon system and round. What is the origion of the typical 40 MM AA round, SWISS?

The 20mm gun is Swiss. The 40mm is Swedish. How about a photo of 1 or some of your favorite rounds with a Tiger or Lemur. Not just every collector has those in their collection. I have a bird !

Haha! I will try! I have a cool APFSDS 30 MM round a lemur could hold? Just kidding. Thanks for the information on the 40 MM origins.

Here is anouther 20 MM gun that looks very much like the one this sight went to. Note the photo of the assumed correct 20 MM round of the era.

APFSDS, the gun shown seems to be a 20x110RR Oerlikon but the shown cartridge is a 20x139 for the M139 gun.

Thanks EOD! You have a great eye. I guess thats why you are EOD! I do not know much about 20 mm rounds other then they seem to have a gazillion types. I have a realy interesting 20 mm round. I was told it is German made for the US? I’ll post a pictire of it shortly to see if any of the experts here have any info on it.


Well, I recognize (sometimes) what I see because I’m interested. Most EODs will not and frankly said it is not really their job.

Just changed the thread title to properly identify subject matter :-)

Here’s a “posed” photo of 20mm with the MK 14 sight on the USS Iowa ca. 1943. Note that the radar antennas on the mast have be blurred by the censor. As late as the 1950s if a sailor was caught taking photographs of the fire control apparatus his camera and film were confiscated. Don’t ask how I know this. In the 1990s the President of the United States was giving away much more valuable inormation for free.


Besides the subject matter, that is a GREAT PHOTO! Thanks Ray!

PS: I wont ask! :-)

Yes! That definitely looks like the same sight on the 20 MM! It must be weird firing that gun looking threw a sight that points in a different angel as the barrel?

This is what these guns are all about. A selection of 20mm long Oerlikon shells from Bob Hawkinson’s collection.

Is the 20 MM round, 7th from the right, made completly out of Bakelite? They are all nice pieces. Thanks for adding that photo to the thread.

It is made out of wood. It is a drum loading dummy.

Awesome! What is a “DRUM LOADING DUMMY”,?

On these Gaitling gun systems the ammunition is stored in a “Drum”. A drum loading dummy is used to test the feed system after maintance. Here is a picture that shows the drum at the back of the picture. The cartridges are stored in slots inside the drum, hanging from their rims.

Fantastic! You rule! That explains it. So true about a picture being worth a thousand words. Of course, now it makes perfect sence.