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2 pounder 40 X 275RB AA case

Quatermass

Quatermass

Well-Known Member
Has anybody got any information on this experimental 2 pounder case?
Brass tapered necked, dimensions are 40 X 275RB, rim diameter is 55mm and
its stamped 2PR 75CAL DDL16484A RL N 1944 4
Third photo shows a comparison between 40 X 304R, 40 X 275RB & 40 X
157R.

2PR75CAL3.jpg2PR75CAL2.jpg2PR75CAL1.jpg
 
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Hi Q,

Wow, what a beauty, never seen one before. Where on earth did you manage to dig that one up from?? Yet another case type to keep my eyes open for.

Roger.
 
I got it from ebay Roger, I'd asked the seller a question, the auction got pulled by ebay and he offered it to me. A case of the right place right time.
 
I saw a sectioned version of an almost identical case (except slightly longer at 40x285RB) many years ago, and still have a drawing of it in my files. Rim diameter 53mm, body diameter 60mm. I formed the view at the time that it was probably for an API blowback, not only because of its shape but also because the case is massively thick at the base, indicating that it was expected to resist considerable pressures without much support from the chamber walls. I have no idea what it was for, but at least the headstamp on yours tell us it was probably American (at least I assume so from the "75CAL") and gives us a date (the one I saw had no h/s).

It bears a remarkably close resemblance to a double-sized version of the German WW2 experimental MK 108/20 case, which was 141mm long with a 26mm rim and a 32.4mm body diameter.
 
Aha, so I was wrong about it being American. Can't recall seeing a "75CAL" type designation on a British case.

I wonder what they fired it from, and why they bothered given the fact that the excellent Bofors was in service? I've never heard anything about an experimental 40mm automatic gun at this period.
 
Thanks guys, I new somebody would know what it was. Now I just need to find out a bit about the gun and a projectile to go in it......
I'd agree Tony about it being for a API blowback weapon as the base is very heavy.
Thanks again.
 
Tony Williams said:
...... I have no idea what it was for, but at least the headstamp on yours tell us it was probably American (at least I assume so from the "75CAL") and gives us a date (the one I saw had no h/s).....
Click to expand...

Shame on you Mr.Williams! Headstamp is "2PR 75CAL DDL16484A RL N 1944 4". It was made at Royal Laboratory, has a British Design Department drawing number and is marked to Naval service!

100 lines by tomorrow!

Cheers
TonyE
 
It was for an experimental close range weapon for Naval Service. Work started in February 1943. I believe BSA produced the ordnance.
 
Coincidently I was just trying to find some more information. The minute of the Navy meeting that seems to kick this off talks about getting a better performance than the "present 40mm Bofors", a higher velocity and higher rate of fire are both mentioned.

I'll see what else I can find.
 
Q,

The project was abandoned in 1946 and it is not clear whether only 'pressure barrels' were produced by BSA or the complete gun. A number of designs of projectiles are mentioned in OB Procs but it is likely that only proof and practice projectiles were actually produced. Mention is made of manufacturing of 1000 cases of the design you have, also mentioned is a recommendation to ROF(Woolwich) [RL] that an aluminium case is designed (your next quest!).
 
Shame on you Mr.Williams! Headstamp is "2PR 75CAL DDL16484A RL N 1944 4". It was made at Royal Laboratory, has a British Design Department drawing number and is marked to Naval service!
Click to expand...

Headstamps aren't my strong point - it was the "75CAL" which fooled me, a very American-looking designation! :tinysmile_angry2_t:
 
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Bonnex said:
Q,

The project was abandoned in 1946 and it is not clear whether only 'pressure barrels' were produced by BSA or the complete gun. A number of designs of projectiles are mentioned in OB Procs but it is likely that only proof and practice projectiles were actually produced. Mention is made of manufacturing of 1000 cases of the design you have, also mentioned is a recommendation to ROF(Woolwich) [RL] that an aluminium case is designed (your next quest!).
Click to expand...
Fascinating - this may have been the precursor of the postwar Red King and Red Queen projects, although they were for the army rather than navy.
 
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Tony Williams said:
Headstamps aren't my strong point - it was the "75CAL" which fooled me, a very American-looking designation! :tinysmile_angry2_t:
Click to expand...

I should not worry about it Tony, we all do it at one time or another!

I just like a wind-up!

Hope to see you Saturday,
All the best,
Tony
 
Thanks Bonnex, you wouldn't happen to have a drawing of the projectile 'HE S/L 2pdr. HV' used with this case? I'm planning to get a dummy projectile manufactured and a good drawing would help.
Thanks again.
 
DD(L)14214 Shell QF HE SL 2Pr AA

Quatermass said:
Thanks Bonnex, you wouldn't happen to have a drawing of the projectile 'HE S/L 2pdr. HV' used with this case? I'm planning to get a dummy projectile manufactured and a good drawing would help.
Thanks again.
Click to expand...


Hope this is good enough:


DD(L)14214 Shell QF HE SL 2Pr AA.jpg
 
DD(G)467 Ordnance 2pr 75 Cals Automatic Gun

...and this is the Ordnance. Several Cartridge types were designed. In time I will put copies of the drawings in the download section.


DD(G)467 Ordnance QF 2Pr 75Cals Automatic Gun.jpg
 
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