20mm Oerlikon Disassembly

[longlever]

Hello!

I'm a volunteer aboard the SS Red Oak Victory, a World War II "Victory Ship" in Richmond, California. I have recently been tasked with the job of rebuilding two of the ship's 20mm Oerlikon Canons, since I am one of the few on board who is familiar with firearms (I collect Martini-Henrys, and run www.martinihenry.com). Yes, the Oerlikon is only slightly different than a Martini-Henry :)

Anyway, we have two WWII era Oerlikon guns, with mounts (pictures here: http://martinihenry.com/temp/albums/rovguns/). From what I'm told, the Westinghouse mounts are not technically correct for the ship, but will serve our purposes. The guns are pretty rough and will definitely need restoration. The other six 20mm guns we have are Vietnam Era, and will be a much later project. For now, we're wanting to focus on these two period pieces.

Anyway, I was wondering if anybody has disassembly instructions for this weapon? Also, does anybody know if the correct color for the recoil spring is black, or red? Does anybody have any comments on the guns that can be gleaned from these pictures?

Many thanks in advance for the assistance!

Jason Atkin

[small arms section]

Jason
I have two manuals for the 20mm Oerlikon Guns used by the US Navy. One is Ordnance Pamphlet No. 826, “20mm Antiaircraft Gun – Mark 4 and Mark 2”, dated July 1942, 93 pages with one big foldout. The other manual is, Ordnance Pamphlet No. 911, “20 mm. A.A. Gun”, dated, March, 1943, 232 pages with one big foldout, and a complete parts list. Both of these manuals have information on ‘Maintenance, Stripping and Ammunition”. The 826 manual also has ‘Gun Drill’ information. The 911 manual has more detailed information on ‘Maintenance & Stripping and stuff on the sights and mounts.

I will contact Eric Nicolaus,, (Nicolaus Associates) and see if he will copy these manuals for you.

You might get a copy of George M. Chinn’s, “the Machine Gun” it is available on disk, and I ‘think’ it has a section on the Oerlikon. I will look thru mine tomorrow and see if it has anything.

There are two barrel springs (front and rear) the older type had a rectangular cross section and the newer type had a round cross section. I have not looked thru these manuals for quite a while and I do not remember anything about red or black springs. But some (or all) of these barrel springs have yellow paint to denote front or rear. I will try to go thru the manuals tomorrow and see what I can find.

DO NOT try to disassemble those guns without a instruction manual. The barrel springs are under a great deal of pressure (compression) and if not removed correctly, they can fly out and cause injury, if they strike someone. I have heard a story about a sailor being killed when struck in the stomach by one of these barrel springs.

I will let you know what happens.

Small Arms Section
45B20

[small arms section]

Jason
You could also contact Tony Williams on the Cartridge-Ordnance Collectors Board. He is very knowledgeable on the big stuff. He has written a book or two on the subject.

Small Arms Section
45B20

[longlever]

Thank you, Small Arms Section! Great information! I definitely wasn't going to attempt disassembly, save for possibly taking the gun off of the mount. The mount weighs a ton (literally) and needs the most attention as far as restoration goes. Although, it sounds like it might be easier to strip it when it's mounted...well, I suppose I'll have to learn as I go along! In the meantime, I plan to chip the paint away from the nuts and bolts, and spend the next couple weeks soaking various parts of the gun in penetrating oil in preparation for tear-down. Any thoughts on a paint type I should use?

[garnettstancil]

Sarco has a COPY of two manuals for these 20 mm U.S. Navy guns. They charge $75.00 for it and it is just copies of paiges, NOT a re-printed manual. Contact Machinegun Dave at Sarco. He might give you one free for your museum project. Best Wishes!

[The Wizard]

Longlever,

If the SS Red Oak Victory is a nonprofit group SARCO can write off the cost of the manual on their taxes. You might want to mention that when you contact them.

By the way my dad served in the Merchant Marines both on a Liberty and Victory ship during World War II (Interesting story behind his service). In fact, he sail out of San Fransico. Met my mom, she was from Alamedia, there. They lived in San Jose until 1974 when he retired and moved back to Couer d'Alene, Idaho from where he set out back in 1942.