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Naval 2 pounder question

Burney Davis

Premium Member
The naval two pounder gun saw service in the first and second wars. During the intervening period it was used as a sub-calibre round and the case was used for launching depth charges. The standard case is 40 x 158R and these turn up dated in the 1930's and over stamped as sub-caliber for Low Angle firing (LA). Some of these cases are shortened to 107mm and overstamped as sub-calibre for High Angle (HA) use.

Does anyone have any information on what projectiles were used in the sub-calibre LA and HA rounds? Also, why would the case have been shortened for the HA use? I am aware that the rounds were used as sub-calibre to 6 pounder guns, but what other guns were they used in?

Thanks in advance.

BD :tinysmile_grin_t:
2pr sub cal

sorry no answer yet to above question but can add I've never seen a practice proj (and there are a no. of variations) marked as sub cal and was told they probably used std practice ones. I can add that the 107mm long case with part knurled rim does appear stamped 2PR NO.3 RL 1940 but with no N to indicate naval service so it would appear that the short round was in use during WWII. None of the Treatise or hand books I've got are any help but the questions raised are some I'd also like to resolve so am working on them.

Here is a picture of an overstamped case. The latest reuse is 1946 and this one is stamped 'N' for naval. Did the British stamp any of their projectiles 'sub-calibre', as I can't ever remember having seen one? I know the Americans did on some of their 37mm WW1 rounds.

How many variations of practice projectiles were there?




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Shortened 2 Pr cases were used as 'clearing charges'. However, they were used with a full charge, which contradicts the CRR above 1946 assuming this is the charge status and not a repairer's monogram.

There was a 2Pr MkII CHA mount

S on a case, after the mark (which it isn't) denotes repair by bushing.

Milled rims denote cartridges for star shell or drill


Tim. G.
2pdr. SubCal

I had one of these cases a while ago, I found images as you see. The primer image is too poor to use. It was a full length case. As the subcaliber device was likely a standard 2pdr. barrel with bushings made to centre it in any given bore, it is likely standard projectiles were likely used. If fired at targets on water the projectiles were likely plugged, the splash giving the required effect. But I have never seen any official information. Vikers Archives might help as they likely suppied the equipment.


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1915 2 Pdr.

This won't help the subcal question at all. But I had this image from the person who sold it years back. Clearly the projectile is derived from the 1 1/2 Pdr. and has the upper band soon discontinued.


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2pr practice

I've seen 2pr practice shells of 3 types, details below;
a. VI/N 2PR HV B S P 6/42 with conical truncated plug
b. I/N 2PR P B S 5/40 with blunt ogive and big truncation to plug
c. badly corroded with long ogive and 2 spanner flats to plug similar to 11/2pr practice shell so I guess an early type

B S indicating billet steel and P for practice.

The 1945 Naval ammo handbook lists fuzes for 2pr HV and other fuzes for 2pr LV so one cant assume NOT HV implies sub cal but that the navy were running two gun types and hence needed two ammo types with different ballistics (supply must have been fun).
LV & LV 2pdr.

I find it hard to believe any of these AA rounds could be considered HV with their large projectile on a relatively short casing. It is like comparing a revolving cannon 3pdr. round with a long cased navy 3pdr. But is there such a thing as a long cased 2pdr. in navy service ? If not, perhaps LV are subcal ? and the difference in rounds is not the projectile but the charge in the case and the fuse. The 1937 case I posted shows filling information on the stencil (I think), is this different that the regular AA loading ?
2pr LV & HV

There was no long cases 2pr in Naval use but the 2pr AT case did use the same HE proj as the shorter naval pom pom these are late or post WWII if my memory is correct. I've always niavely assumed that sub cal rounds were practice and not filled with an explosive of any sort, and therefore not fuzed, am I wrong?
also 2 sub cal headstamps the HA is the short case version. Does anyone know any old sailers who might be able to advise on this subcal stuff?


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Subcal practice

Wether they are charged with an explosive filling or not would depend on the target. If at a vertical paper or cloth target or a floating target no explosive would be needed. If the target was on land some sort of explosive filling would be needed or the fall of shot would be unseen. This is the way the U.S. subcal projectiles seem to be organized. The U.S. Navy and Army Coastal artillery 37mm projectiles are blind loaded and or plugged as the targets are mostly on water. The Land Artillery uses fused exploding projectiles.
Sorry to be a bit late with this one but I've only just arrived...

The 40x107R case (of which I have an example in my collection) was for the HA (for High Angle) AA training gun. This was a completely separate manually-loaded weapon on its own mounting, not attached to a bigger gun. See the diagram below, which I found in the Leeds Armouries library:

....ah knowledge is a wonderful thing Tony!! Do you know what projectile(s) went in these cases? And why would they call a stand alone purpose built gun a 'sub calibre' gun?

I have a vague recollection of reading somewhere that it used standard 2 pdr projectiles, but I could be wrong.

I assume it was called sub-calibre because it was used to train AA gunners who would normally be using larger guns, like the 3", 4" and 4.7". It was just a mini version of one of those, used to save on ammo costs (and probably also avoid wearing out the service guns).
2 Pndr

Hi ,, I have this one ,,it's not really my thing but it has been with me for 20 years + . I hope there's attatched info that helps, the original clip is the uncleaned one, the other is one i picked up from Stonliegh show.



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Top pics there Jeeensy!,
What are the stampings on those links i looked at yesterday pal?


I have now discovered some more information (extracts from the gun's handbook from which the above illustration came, plus more data in Campbell's 'Naval Weapons of World War 2') These prove my memory false, so I need to correct some of the things I posted above. What follows is my interpretation of the mix of information in my two sources.

There were two sub-calibre 2 pdr guns, designated High Angle and Low Angle. They were designed to fit within the barrel of 4" and 4.7" naval guns, and used the breech mechanism of the parent guns. At some point it was decided to make use of these for more warlike purposes, so they were fitted with a percussion breech mechanism and had a dual-purpose mounting designed, capable of taking either gun. That is what is shown in the picture above. So they were for active service, not training as I said.

In the Handbook, the Mk XI was stated to be used in Q.F. guns, the Mk XII in B.L. guns (which I find odd because Campbell lists all 4" and 4.7" guns used in WW2 as Q.F.). The Mk XI appears to use the short-case (40x107R) round as this is stated in the Handbook as weighing 2 lbs 10 3/16 oz while the Mk XII round is stated to weigh 2 lb 15 1/2 oz (and is presumably the standard 40x158R round). The muzzle velocities with a 2 lb shell are given as 1,900 fps for the LA gun (about right for the pre-WW2 40x158R ammo) and 1,100 fps for the HA gun (Campbell says c.1,200 fps for the Mk XI and 2,040 fps for the Mk XII).

Campbell states that the Mk XI had a 25-calibre barrel, while the Mk XII had a 40-calibre, which also supports the conclusion that they had different case lengths. Therefore, it is safe to conclude that the Mk XI used the HA gun and the Mk XII the LA gun. He also states that 180 Mk XI guns and 170 Mk XII were produced and fitted to HDMLs (Harbour Defence Motor Launches) and other small auxiliaries, and that case shot was also provided as well more conventional ammo, at least for the HA. The implication is that both HA and LA cartridges used the same projectiles.

To put all that together, it seems that the Mk XI was the HA gun firing 40x107R ammo and in its sub-calibre training form was probably originally intended to work with 4" and 4.7" HA (anti-aircraft) guns, while the Mk XII was the LA gun firing 40x158R originally for sub-calibre use with surface-fire weapons.

I hope that it's now a bit clearer. :tinysmile_eyebrow_t