Sir John Valentine Carden Survives. Part 2.
- Thread starter allanpcameron
- Start date
I'm not entirely sure that you are right on that one unless I am misreading what you are saying.
The OTL 75mm HV was proposed by Vickers (as you said) in early 1942. The gun was proposed for the Cromwell and used the 3" 20cwt case mated to the US 75mm projectiles, both the M61 APCBC and M48 HE. The reason why Vickers chose to use the US projectiles for their new gun is unclear, as is the reason for the switch to 17pdr projectiles later though I have my suspicions. The 17pdr was never considered for the Cromwell as far as I am aware although their was concern from late summer 192 (I Believe) that the 75mm HV would not fit. It was only realised in March 43 that the gun definitely would not fit. The suspicion that it would not fit seemed to have been the drive for the OTL development of the OQF 75mm.
Not to my knowledge.
The whole process for proposing a foreign (though admittedly in service) shell is a puzzle. There could be something to the idea that Vickers knew the US 75mm was getting good reviews and took a gamble because they could make a 75mm Barrel fairly easily but that is a stretch for me. Several months before (Mid 1941) the UK had settled on the 17pdr as its next towed anti tank gun. If the goal was to get British acceptance then surely adopting the 17pdr projectile would have been a better move to ensure adoption. The sales pitch of our new tank gun uses the same projectile as your new anti-tank gun would have appealed.
The decision to use American projectiles in a British gun suggests, to me at least, some form of official guidance at minimum. Now it could be as simple as you suggest but I am rather sceptical. Again the UK had a new 3" gun working up so why not suggest commonality of shell with that?
What makes the whole thing more puzzling is that the Shell casing from the 20cwt AA gun was in 3" calibre. That means that Vickers took a 3" case and necked it down to 75mm. After that went nowhere they then went back to 3". We know that Vickers could produce 3" guns so it isn't as simple as expediency driving the adoption of a new calibre. In fact the 3" 20cwt already had an AT round available for it before the 75mm HV project started so why not use that? It was only slightly less effective than the theoretical 75mm HV performance of the M61 APCBC round at 1000 yards IIRC. That round did have the advantage of being produced domestically in the UK, something which never happened with 75mm ammo of any type during the war to my knowledge.
Again the whole thing remains a puzzle. I do have a theory but no proof if any proof even exists.
Oh ffs! How many more times do we have to relive this whole 75mm/76mm/not again.5 mm gunmalarkey? Let Allan write the TL and leave these tedious arguments alone.
I agree! Let's focus on the real issues here... the caliber and other projectile characteristics of the small arms carried by the tank crews!
This time, I think it's less a debate about what should be done, and more confusion about what is being done.
N
If a factory has the tooling for a 76.2mm gun then it already had the tooling for a 75mm gun.
The limitation is the barrel length and otl this was a lathe issue.
No you misunderstand.
If a factory has the tooling for a 76.2mm gun then it already had the tooling for a 75mm gun.
The limitation is the barrel length and otl this was a lathe issue.
Ramontxo
Donor
You mean having an 4,5 inches gun in the RN (adopted by the British Army as heavy AA gun) that was incompatible both in the RN, and its British Army heavy AA gun derivative, between different marks using fixed and separate rounds?
Sorry I had forgotten that the British Army used an long range gun of the same caliber but, of course, totally not compatible.
You do know there are very good reasons why that happened? Small ships without power assist needed lighter shells to manhandle, hence separate rounds, larger ones with power got greater rate of fire out of fixed rounds ( they were also slowly groping towards unmanned turrets ). Naval guns will also always be different from mobile land ones, ships don't care about weight as much and have a different set of constraints. So an optimised naval gun will have a greater rate of fire than its land based equivalent ( its why some shore batteries were just naval turrets in a concrete bunker. ) , hence the differing marks/types
Ramontxo
Donor
I am sure that the whole amount of (incompatibles) 4'7, 4'5 etc diferent marks were also as logical
Also, a ship is (mostly) its own supply train, so stocking multiple rounds isn't quite as much of a problem in the navy as it would be in the army. It'd probably be a bit simpler if they did standardise a bit more though.
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All of the individual decisions were sensible in isolation but the cumulative result was that the RN had an absolute mess in the medium calibres that was a problem.
Not to mention the switch from 15-inch guns to 14-inch for their battleships. A more minor issue, but when every one of your capital ships but 5 of them use 15-inch shells, sounds like a headache for the people in charge of logistics.