Unknown cannon/gun shell casing what is it?

Iam new here I have had this shell casing for years and have no idea what it is or the type of cannon/gun it was for.
Also I would like to know if it has any value.
The dia of the bore is aprox 2 1/4 inches its a straight through shell with its primer in the middle of its side also has a locating pin at the rear.
The markings are G.O. Co. 6- PDR Mk 3 Lot 9 3-16 I assume its 1916 vintage.
I took some pictures but have to figure out how to post them.
Any help is greatly appreciated !

With no more information to go by, I’d say you have a case from a USN 6 Pounder (6pdr). The projectile measured 2.25" in diameter and the case should be about 12" (307mm) long. It was used on small ships and vessels during the late 19th and early 20th centuries.

Post those photos and we can pin it down.


Thanks for your reply it measures 15 3/8 inches long I cant figure out how to post a picture but I could Email you them if you send me your Email. Thanks

Todd–Read the post at the top of the page entitled “How to post images” to learn how to post images on this forum.


I got the photos. Not what I was expecting to see. Not even close.

I’ll get back to you when (if) I find out what it is.


With the primer in the side of the case it sounds like a 6 Pr. Davis gun, an early recoilless rifle.

It fired A charge of lead shot rearwards to counterbalance the shell.

It was used by the British in WWI as well as the 2Pr and heavier 12Pr. version.

Compare your case to the attached drawing of the 2 Pr…



I can’t post a picture but can direct you to a good diagram for the Davis gun ammunition used/tested by the US Navy during and after WW1, the 6 pdr is shown at the top of color Plate XIII, located in Ammunition Instructions For The Naval Service, 1923 which can be downloaded here: archive.org/details/ammunitioninstru00unit

Also see on BOCN, here bocn.co.uk/vbforum/57-x-390- … ght=davies

The Davis gun was tested by both the US and British during and after WW1 as an aircraft mounted “recoilless” gun system.


I posted your photos on BOCN (British Ordnance Collectors Netwok) which is where Tony’s reply originated. You can take his ID to the bank. And if you decide to sell it, you will probably take some cash to the bank also. Apparantly it’s one of those holy grails of ordnance.


All I can say is Wow Thanks ! You guys Ray, Tony, bdgreen nailed this ID I had no idea how important this shell is in the early development of the recoil less guns I have had this thing lying around for years I think someone gave it to me before they were going to throw it out.
I really appreciate all your help !
But I would like to know what you think is a realistic value of this shell
Thanks again Todd

The manufacturer’s initials stand for General Ordnance Company, Derby, Connecticut.

Wow Fede that is really interesting I was wondering what G.O.Co. and ironically Derby Ct is 5 miles away from my house and I never knew that Co was there I will have to research that Co.
Thanks again for your input.