5/25 Deck Gun Information & Photos

[tom dougherty]

For those who might want to scratch build a 5/25 gun for their Gato (or Balao) model, here are some photos. The 5/25 was installed later in the war (August, 1944 on), and replaced the earlier 3 & 4 inch deck guns. The initial 5/25 Mark 40 fired a 5 inch, 53 lb shell some 14,000 yards. The particular gun pictured is off of USS Flasher (SS-249), and is newly restored on the grounds of the US Submarine Force Museum & Library, Groton, CT. [b] Note] the optical parts of the aiming gear are not mounted on this gun.

First, a 5/25 diagram from Tom Wackowiak (Gato & Balao Plan Book):




Digital photos taken at Submarine Force Museum & Library on 12/27/2006, by T. Dougherty. These are high resolution (click the photo) images of the 5/25 gun][/url]

[himszy]

Tom,

Out of interest, what does

Tom,

Out of interest, what does the 25 mean?

Michael

[tom dougherty]

Tom,

Out of interest, what

Tom,

Out of interest, what does the 25 mean?

Michael

It means you must be 25 years old or older to operate this gear...
No, really, it stands for 25 calibers.
Tom

Addendum Sorry, I was tired last night. As Jeff says below, the 25 calibers means the gun is 25 times as long as the 5 inch diameter (caliber) of the shell. Hence the barrel is (5" X 25 = 125") or 10 ft, 5 inches in length. In contrast, the earlier 4/50 gun shot 4 inch shells and had a barrel length of 200 inches, or 16 ft, 8 inches.

[JWLaRue]

re: 5/25

....and 25 calibers means

re: 5/25

....and 25 calibers means that the length of the barrel is 25 times the caliber (5 inches) of the gun. For some reason, this is how the U.S. Navy denoted naval rifles.....

Tom, I'm guessing you can explain why it was done that way?

-Jeff

[cody]

Tom
Thank you very much for

Tom
Thank you very much for posting your pic's!
Brings to light a bunch of little detail's.


Jeff

[kagnew]

TOM
you did great!
how far do

TOM
you did great!
how far do you live from this gun?
will they let you take a tape measure, and get me some dimensions?
i think i can make some in 1/72 scale if i have some numbers.
i mean if i can build real guns,i should be able to do a model
glen

[seadog]

Thanks for posting tom.
juist the

Thanks for posting tom.
juist the information that I was looking for.

[kagnew]

Tom
does the 125" just include

Tom
does the 125" just include the barrel, or also the breach assembly?
if i get that right i can figure the rest from information you have posted.
thanx glen

[boss subfixer]

Tom,
In light of the recent

Tom,
In light of the recent trouble you have had in posting pictures I just wanted to say Thank You for putting up these of the 5" 25. I have a white metal set in 1/48th scale and due to your pictures this jumbled up mess finally makes sense.
Don

[dietzer]

Tom,

Many thanks for posting these.

Tom,

Many thanks for posting these. You got some great pics of this gun!

For those who may be interested, Floating Drydock has an 8-page ordanance pamphlet on the gun, with scale drawings. The pamplet is called "OP-17 5"/25 CAL. OPEN SUB DECK GUN" and is available here: http://www.floatingdrydock.com/ordnance.htm.

A couple of years ago I stumbled onto a website that sold old military training videos on VHS tapes. They actually have one on the 5"/25 deck gun! I don't have the url with me at work, but if anyone's interested in this I can post it this weekend.

Carl

[tom dougherty]

Thanks for the great feedback

Thanks for the great feedback on the gun pictures. I think I also have the posting fixed (thanks to all for great suggestions on solving that little problem!!), as I posted some more Russian sub stuff I had on the Wayne's Russian sub-site.

I think I just about covered all of the details in the photos. Let me know if anyone needs anything in particular on this gun, as I am close by to it.

Tom

[subshop]

5/25

anyone have detailed drawings they could post? neil

[ricknelson]

One item that is missing

One item that is missing from pictures taken of a 5"/25 that has been removed from a boat is the "adapter plate" and "cam follower ring" at the base of the mount. I don't know if these are the "official" terms for the items I'm about to describe but they reflect what their purposes are.

The "adapter plate" fits between the 5"/25 base mount (the item with all the bolt holes and 45 deg. supports) and the built-up superstructure portion of the submarine which has a different, more generalized bolt hole pattern. I have seen a picture somewhere (most likely Floating Drydock book) of a boat that has had it's gun removed and shows the general supertructure mounting platform. Keep in mind that subs were designed for the 3" and/or 4" guns and the 5"/25 had to be adapted to the existing superstrucutre.

The "cam follower ring" is mounted on the adapter plate and is used to keep the 5"/25 from shooting portions of the sub, like the bow/stern and the fairwater. If you look at the last picture Tom posted you will see a spring-loaded vertical brass rod. On the bottom end of this rod is a follower that would ride on a cam ring. The cam ring would be designed such as to force the rod up and therefore the gun up in elevation any time the gun was trained in a position that a shot would be detremental to the sub. Again, this is usually only seen on guns that are mounted on a boat. When viewing the front side of the gun mount you would see that the cam follower ring would have a lobe to prevent the gun from shooting off the bow or stern depending on whether the gun was located forward or aft of the fairwater.

There are a number of photos in the various references that show the "adapter plate/cam folower ring" implementation on different subs. These two items are usually missed by the aftermarket guys because they do not show up in the drawings for the guns as they are unique to a given boat, the position of the gun on the boat, and would be part of the drawing package for that boat. Keep in mind that the same mechanisms are/were present for the 3" and 4" Gun mounts also.

I've found two pictures taken aboard the Lionfish at Battleship Cove in New Bedford, MA. The gun is aft of the fairwater and pointed at the fairwater. Therefore, in the first picture which is of the front of the gun one can see the cam follower ring lobe for protecting the fairwater. It is actually a "stop" so the gun cannot travel any farther. The gun elevation rod happens to be hard against it in this photo. That's my grandson playing gun pointer.



In the second picture which shows the rear of the gun you can see the lobe on the cam follower ring which will force the barrel up in elevation to protect the sub's stern.



Just an additional point of interest, the USS Lionfish, SS-298, is a Balao-class boat but Revell has labled their 1/178 Gato kit the Lionfish. Revell had also at one time called their kit the Flasher, SS-249, and before that I think it was called the Growler, SS-215.