US Navy Mk 23 Nuclear Projectile for 16"/50 Mk 7 Gun

US Navy Mark 23 Nuclear Projectile 16"/50 Mark 7 Gun

While doing a search for another subject, I ran across a reference for a nuclear 16

I did not know anything about a nuc round for the big guns. Not shocked to hear about it but surprised I never heard of it before.


The US had both a land Nuclear Cannon and the Navy version. There should be photos on the Internet somewhere.


I was aware of the Army’s 280mm Nuclear Canon but had never seen or heard anything about a nuclear projectile for the Navy’s 16 inchers.

This item from the same web page should interest Jason (APFSDS):

  1. In the spring or summer of 1967 when USS New Jersey (BB-62) was being activated for Vietnam, Indian Head Naval Ordnance Station proposed taking 23,000 non-nuclear 280 mm (11") shells left over from the Army’s “atomic cannon” program and converting them via a sabot and obturator to be used in 16" (40.6 cm) guns. This was apparently a part of or in conjunction with the “Gunfighter” program for developing Long Range Bombardment Ammunition (LRBA) projectiles. Test shots were fired in 1968 and 1969 at Yuma and at Barbados, with the latter location using two 16"/45 (40.6) cm guns welded end-to-end and achieving ranges out to 83,850 yards (76,670 m) with a 745 lbs. (338 kg) shell fired at a muzzle velocity of 4,550 fps (1,387 mps). The program was apparently halted when New Jersey was decommissioned in 1969. An image of the disassembled saboted round is on the additional pictures page.

Talk about a long shot!!

I would like to know how they managed to line up the two barrels well enough to weld them together. Obviously the alignment would have had to have been exact, down to probably below 10s of thousands of an inch. I also wonder what welding process they used.

Falcon, if you mean the Davy Crockett (or any coaxial gun / spotting gun). The mount of the smaller caliber gun is fixed in a way that it can be adjusted and zeroed in. Often by dove tails or excenter bearings etc.


Just a SWAG on my part but the welded tubes most likely had a finished diameter rifled liner. Or, if the projectile was FS, a smooth liner.


EOD: I’m talking about the welded 16" Battleship guns that pbutler posted in the post above mine.

Ray: by saying “Welding two 16” barrels together, i took it to mean two existing barrels.


I took it to mean the same thing. But, I’d guess that the welded together barrels were bored out and lined rather than trying to do the impossible - line up the rifleing of the two barrels. I’d also guess that the exterior was turned and a sleeve or hoop fitted to the breech end.

Lots of ways to skin that particular cat.


I would like to see the lathe they used to turn the exterior.

Oh well, I slipped on the various nuke threads now, sorry.


That lathe is probably a little bigger than you and I are used to seeing. A little searching on the Internet would probably turn up a photo.

In olden days, a big barrel was turned on a gigantic set-up by holding the rough tube in a fixture and then having the cutting tool rotate around it. Kinda like an exterior boring bar. Boring for the liner was done the same way - by fixing the tube and rotating the boring bar.

AFAIK they may still be done that way.


It appears that some of the 16" (and other large caliber) Navy gun barrels were made at the Naval Gun Factory in Washington DC.

Much of the repair, relining and overhaul was done in Pocatello, Idaho.

For a good account see

After the last decomm of the battleships, the Pocatello facility was closed and the tooling sold off. Perhaps even earlier, but they were still in operation in the late 1960s.

The grafted together pair of 16"/45 barrels were for the HARP program led by Gerald Bull.


Watervliet Arsenal in NY made many of the big guns, from the American War of the Rebellion to the present day. Maybe we can get SKSVLAD to drive over and take some photos of the big machinery for us?



OK, a couple of my machinist friends sent me to this site. You’ll like it.

I think this machinery is in the UK. Maybe it’s still there.

Ray … watervliet

It really would be interesting to see some of that stuff.

There is some threads on showing photos of the on board machine shops on museum ships, which are interesting. I took some photos of the one on the HMS Belfast when I went round it. Someone on that forum said his dad worked in machine shops on board US Navy ships (i think during WW2).

Apparently sometimes one of the bolts securing a machine to the floor would break in rough seas, meaning that the machine could come loose from the floor if any more bolts broke, which is obviously not good. Apparently what they did about this was sent someone in to weld the machine to the floor at the corner where the bolt broke before this ship rolled again. I imagine not an easy job with the ship rolling. The guy ended that pragraph with “Any volunteers”.

We were posting at the same time. See mine above yours.


I had the pleasure of getting a nice tour of the Watervliet Arsenal in the early eighties and can tell you that the lathes used for the 16" guns were VERY BIG by most any standard. They were tooling up to re-fit the Iowa Class ships recently recommissioned by Ronnie R. No pictures were allowed but there might be some archival photos out there somewhere.
The most impressive memory I have was watching a 175mm tube (if my memory serves, they also did 155mm and 8" at the time) being rotary hammer forged from a raw billet that came on a rail car into the facility. After heating to some crazy temperature it made its way to the forge for rough forming on a mandrel. The radiant heat was staggering as was the noise and impact energy of the operation. The heat treating and machining operations were impressive also, but the rotary hammer forge operation was something I’ll not soon forget.
They have some of the big barrels on display getting all rusty in front of the facility you can see from I-787. Since security has calmed a little, I understand that the museum is open to the public again. To my knowledge, no public tours of the manufacturing if they are doing any at all there at this time. On my list of local visits to take…


Excellent photos Ray. Unfortunately the machinery is definitely not still there. I doubt there are any machines like that anywhere in the UK today. I would like to see this country try to produce a Dreadnought Battleship using all domestic factories and raw materials today…