3" 23 Cal Landing Gun case manufacturer


I found a 3" 23 Cal Landing Gun case (76.2 x 233R) in an antique shop this morning. Even though I don’t usually collect US Artillery cases, I bought it because I’d never seen one before.

The headstamp reads:


[color=#FFFFFF]—[/color]3" MARK 2
[color=#FFFFFF]----[/color]23 CAL.

I have a few questions about the markings:

  1. Who manufactured this case?
  2. I take it “7-42” is “Lot 7 of 1942”, is this correct?.
  3. What does “L.N.P.” stand for?

Thanks for any info



I can’t answer about the markings other than it’s a USN MK 2 case from 1942, as you’ve already deduced.

Being found in England, there’s a good chance that it may have seen service on a British ship in an AA or deck mount. Many of these guns were sent to England on Lend Lease during the early WW II years.

A good find. Proper projectiles can still be found and would complete the cartridge.



For anyone who is interested, here is a page with alot of info and diagrams of the gun.



MK IX-I Shrapnel from the Meketa Museum.


Nice round Ray, does your case have a primer present or not?

If not, please could you measure the diameter of the inner most hole that goes through to the inside of the case? Someone has put a brass plug in the base of my case, which I intend to drill out. It is secured in by peening the end of it over inside the primer pocket.



Mine has a primer in place. It is a standard looking primer with the four notches for a spanner wrench. It is .800" in diameter. That would mean that the smaller threaded hole into the case interior would be about .550". To be safe, I’d start with a 3/8" drill bit +/- and keep enlarging it until you get to the thread.

Maybe Slick Rick has an empty case without a primer and he can verify the dimensions?



My case appears to be made for a press-in primer. There is an outer cavity which is .475" across by .03" deep. There is then an inner cavity which is .375" across which is where the brass plug is. I can see the other end of it inside the case. I will probably start with a 3mm drill bit and work my way up in 0.5mm steps until the plug drops out.


Your case is definitely different than mine. Mine is a MK V. You should be able to find a primer that fits.

Good Luck



Not sure if I have one. Will check tomorrow.


I got the plug out today. I found out that it was a copper radiator plug that had been screwed into the case. I am unsure whether the thread is original to the case or made by whoever put the plug in. It must have been in there a while as the thread was sealed with hemp. Obviously this case has been used as a vase at some time in its life.