USN 1 Pdr

And now for something more manly.

l) USN 1 Pdr, Common, 1917

r) USN 1 Pdr Heavy, Target w/tracer, 1914

I thought that all rounds with this size case were known as “Heavy 1 Pounder” compared to the usual 37x94R Hotchkiss case.

Is the correct name for this size of case “USN 1 Pounder” instead of “Heavy 1 Pounder”?


The headstamps read:

1 Pdr and 1 Pdr.H

“USN” doesn’t appear anywhere, but the Navy anchor symbol does.

The Hotchkiss is an Army round, I believe.


I think the episode of Pawn Stars with the 37mm Hotchkiss revolving cannon is up again this week on the History Channel.

Falcon (Or anybody else)

I’ve done a litlle research (very little) on the 1 Pdr and now I’m really confused. Apparantly, “Hotchkiss” refers to the guns and the USN 1 Pdr cartridges were fired in various MKs and MODs of a Hotchkiss. I got the impression, maybe mistaken, that the term “heavy” applied more to the gun than to the cartridge or projectile and that a heavy gun could also fire the lighter of the two projectiles. But, the cartridge on the right in my photo is very definitely headstamped 1 Pdr.H which lead me to believe that 1 Pdr Heavy was the correct designation.

Can you (or anyone else) shed any light on this? Those two cartridges are the only USN marked 37mm that I have, so I wasn’t particularly interested in taking this post beyond a little eye candy. But, now I am. I’m always eagar to learn new stuff.


Tony Williams lists this calibre as the “Heavy 1 Pounder” on his site. Other than that I don’t know any more.

Robert Mellichamp’s superb book(s) on all things 37mm should clear up all this confusion. His Volume 1 has been out for about 18 months, and hopefully the expected three additional volumes will appear sooner rather than later.

He covers both the guns and their cartridges, from all the nations using them, both domestic made and contract/export items.

I think that most of this particular are will be in Volume 2, so we may have to wait a bit for the definitive answers.

A reply to my question on another Forum:

[i]All of the 37x136r case loadings (USN) are 1 Pr Heavy regardless of the projectile used. The 37x95 U.S. cases would be considered to be the “Light” loading or round, though the term doesn’t seem to be used as such for these. Other export versions and so on are marked 1 Pr, but would still be a Heavy in USN parlance.

However the Hotchkiss 37x95 loadings are called 1 Pr Light and the 37x120 loadings are called 1 Pr Heavy to differentiate between them. Since the U.S. 37x136 a longer narrower case is an equivalent to the 37x120 more or less the terms seem to have carried along with them. At some point the Heavy term became Official with the USN and the cases were marked as such. I think around 1900.

There are a number of guns that used these including the “Heavy” 1Pr Maxim. [/i]

OK… So both the 37x120R and the 37x136R were called “Heavy 1Pdr.”? Were these exclusively USN rounds and designations?

I guess this to be an example of a 37x120R (but it has no Navy anchor markings) and would enjoy learning of its proper designation and perhaps some history on its use by US or other countries.

Nice items and topic, Ray. Thanks for sharing the pics of your more lengthy 37mm cartridges.


DaveE - I have seen quite a few of that round like yours with that headstamp on the collectors’ circuit.

It makes me think that someone recently found a full crate of them somewhere, as they are all in very good condition for something 120 years old.


Yes, it seems there were a quantity of these found in new condition but not so recently. I’ve had this one for more than 10 years and the gentleman I got it from indicated he obtained it from folks involved in the cleaning out of Bannerman’s Island back in the 1960’s.

I have yet to find a reference to its official designation or the guns and customers for which it was produced.


It looks as though there is a shotshell primer in that Winchester case. Is that what it appears to be Dave or does the picture distort reality?


Yes, that appears to be a battery cup type primer. The O.D. of the cup rim is .500" vs. about .307" for a No. 209 shotgun primer. The interior of the case has a conical protrusion with what appears to be (2) vent slots through which can be seen shiny brass which I assume is the primer’s battery cup. This differs from a typical shotgun shell where the full face of the primer is exposed to the case interior.


Mine have a primer tube that is pressed in. They’re about 2 1/4" long. The primer itself is almost identical to one for a 50 BMG.

It would be hard to light a powder charge as heavy as a case this size would need using only a primer (1000 grains+).


Dave - Someone obviously looked after your round well if it has been out in the open since the 1960s. It obviously was never polished or dropped. In fact it looks good enough to have been made in 1991 rather than 1891, although this is abvoulsy not the case.

The British 1 Pounder “light” (37x94R Hotchkiss) cases also have this style of primer.

Our 6 Pounder (57 x 306R) cases from this era also have this style of primer with no tube inside the case. I believe the bag of cordite which was held inside the case had a secondary igniter charge attached at the bottom.

This is my only experience with any of the 37mm rounds, a piece of trench art (pen cup) from WWI that was in my wife’s family. Her Grandfather was in the US artillary in Europe in 1918.

I just never expected to see a battery cup style primer in such a round but once again I am reminded how limited my knowledge of ordnance really is.


Are you sure that the primer in yours is a battery cup type? I have the same cartridge, dated 1-18 and it has a conventional primer pocket and a conventional primer (approx .320" +/- dia) that looks like it could have come from a 50 BMG. It may be a replacement, I don’t know.


Sorry Ray, I was referring to the Winchester round shown earlier as the one with the battery cup, not the one I show. I’m fairly certain the one I show is completly original, except for the artwork on the outside and I don’t know enough about priming devices to know one from the other. I’ll leave that to you and other experts.


I have only ever seen the single piece primer in these French cases. We see ALOT of these here in the UK. They must have been a popular souvenir from WW1.

My understanding is that PD.Ps loaded those 37-85 cartridges for export as well as domestic use. I’ve been told that if the wood firing plug is painted red, it’s for export. If all this is true it would account for finding them in many parts of the world.