Why Did the Interwar Royal Navy Have so Many Different Calibers?

Delta Force

Banned
The Royal Navy had quite a few different calibers of guns in the interwar and World War II period, which is rather strange considering there weren't many ships being built. Also, unlike the IJN or USN, which would most likely be able to operate out of their home country, or at least nearby ports, the Royal Navy had to be capable of operations across a vast Empire. Given that it wasn't building many ships and had a more complicated logistical situation than any other fleet, why did the Royal Navy essentially operate custom armaments used on only a class or two of ships?
 
There was a mix of legacy issues, new threats and roles and practical concerns. The 3", 4" and 4.7" were all pretty much legacy from WW1, destroyers had the 3" and 4" and destroyer leaders and late war big destroyers shipped the 4.7". These are able to be man handled easily which allows a high rate of fire, perfect for the emerging aircraft threat. However the 4.7" didn't elevate enough for the AAA role so leaving the requirement for the 3" and 4" to be shipped.

The 5.25" was developed to deal with the maturing air threat as well as being heavy enough to take on the small trade protection role in the mould of the small Arethusa class, it being though that a 4.7" wouldn't have enough punch in the surface role.
 
Rain was pretty much spot on with his reply . What you see with the RN is a mix of legacy and a rapidly emerging threat that was not truly understood and resulted in a large number of imperfect solutions .



In retrospect the Royal Navy would have been better off choosing a single calibre that worked well and focusing on it . If you look only at the Royal Navy then the multitude of calibres makes no sense . If however you look at foreign Navies as well you can see why the choice of calibre occurs . The Japanese are a good lesson were they chose the largest calibre that was possible to be hand loaded by their sailors . The French chose the largest possible to mount in order to deal massive damage but ended up with slow rates of fire and no real AA performance . It is worth noting that all RN cruisers built between the wars had the excellent 4 inch dual purpose mount . Purpose built convoy AA escorts like the Black Swan class had the twin 4 inch AA guns .

The Only navy to have a true Dual purpose gun capable of stopping a destroyer and barrage AA fire was the US navy . The 5 inch mark 25 and the later mark 38 although of different propellant case design both fulfilled the two tasks of Surface fire and AA fire very well . Most other navies had guns that were either specialised Surface with some AA or high rate of fire but less damage on surface firing . The American 5 inch mounts held a sweet spot in the mix .
 
Rain was pretty much spot on with his reply . What you see with the RN is a mix of legacy and a rapidly emerging threat that was not truly understood and resulted in a large number of imperfect solutions .



In retrospect the Royal Navy would have been better off choosing a single calibre that worked well and focusing on it . If you look only at the Royal Navy then the multitude of calibres makes no sense . If however you look at foreign Navies as well you can see why the choice of calibre occurs . The Japanese are a good lesson were they chose the largest calibre that was possible to be hand loaded by their sailors . The French chose the largest possible to mount in order to deal massive damage but ended up with slow rates of fire and no real AA performance . It is worth noting that all RN cruisers built between the wars had the excellent 4 inch dual purpose mount . Purpose built convoy AA escorts like the Black Swan class had the twin 4 inch AA guns .

The Only navy to have a true Dual purpose gun capable of stopping a destroyer and barrage AA fire was the US navy . The 5 inch mark 25 and the later mark 38 although of different propellant case design both fulfilled the two tasks of Surface fire and AA fire very well . Most other navies had guns that were either specialised Surface with some AA or high rate of fire but less damage on surface firing . The American 5 inch mounts held a sweet spot in the mix .

Would the RN 5.25in also not fill the bill of stopping a destroyer and AA fire just like the US 5/38??
 
Would the RN 5.25in also not fill the bill of stopping a destroyer and AA fire just like the US 5/38??

Yes but the 5.25 inch while fine for battleship's secondary armament and for the main armament of an AA cruiser was a little on the heavy side for a destroyer mounting. Also the ammunition seems to have been a little on the heavy side for rapid and sustained AA fire.

That said it is a subject of some contention exactly how good the 5.25" dual-purpose gun was and the Dido class for example served with distinction. Overall it was likely was not as good a balance as the 5" inch dual-purpose guns but maybe not a bad gun in itself.
 
Yes but the 5.25 inch while fine for battleship's secondary armament and for the main armament of an AA cruiser was a little on the heavy side for a destroyer mounting. Also the ammunition seems to have been a little on the heavy side for rapid and sustained AA fire.

That said it is a subject of some contention exactly how good the 5.25" dual-purpose gun was and the Dido class for example served with distinction. Overall it was likely was not as good a balance as the 5" inch dual-purpose guns but maybe not a bad gun in itself.

Agreed, the 5/38 was in the sweetspot

but i doubt the RN wanted another calibre so given the choice between a 4.5, 4.7 or 5.25 for the RN i have no idea what i'd do - probably OTL. 5.25 on the CLAA's bigger and 4.7 on the DD's
 

Redbeard

Banned
IMHO the idea of fixed ammunition (shell fixed to a brass holster, like a rifle cartridge) as the future caused most of the problems.

At first glance it would appear the right thing, but with manual loading even a 4,7" was on the heavy side, especially for high elevation mounts. And with automated loading, the mountings simply became overly complex, expensive and heavy.

In contrast the 5"/38, with its good old fashioned separated ammunition created a very workable compromise until more matured technology could produce reliable automated DP mountings.

So while fixed ammo probably was the future, it still wasn't until well after WWII.
 
Actually all major naval powers had a big problem in having many different types of guns in all their interwar designs.

USN played with four, possibly five types of 5 inch guns alone, besides having various 3" and 4" guns for LA and seperate for HA as well in the period, all using dirrent munitions and equipment.

Japan used a lesser number of 3 inch weapons, but had at least four different types of 4.7 inch, mixed between LA QF on destroyers and HA on secondaries for some cruisers and aircraft carriers. 5 inch was split up in at least three types of LA QF weapons on larger DD's and shorter 40 cal weapons on HA mountings for primarily an AA role.
 
I think the size doesn't matter as much as the weight (of shell & loading weight)

Date of service --- Gun ---- Shell weight ------ max Loading weight
1919 ---- 4.7"/45BL--------50lb-------------- 50lb + 14lb bag
1926 ---- 4.7"/40mkVIII----76lb ------------- 76lb fixed
1930 ---- 4.7"/45QF-------50lb -------------- 50lb + 30.5lb separate
1938 ---- 4.5"/45 ---------55lb(or 58sap) ---- 87lb fixed (or 92lb)
1940 ---- 4.7"/5
0 ---------62lb -------------- 62lb + 32.25lb separate
1940 ---- 5.25" -----------80lb -------------- 80lb + 41lb separate
1944 ---- 4.5"/45MKV------55lb(or 58sap) ---- 55lb + 27lb separate
for comparison,
1934 ---- 5"/38 -----------55lb ---------------55lb + 12.3lb separate

I think this suggests that they should just have gone,
(WW1)4.7"/45BL, (1930)4.7"/45QF (and you can just replace old guns as they ware out), (1938)4.5"/45 (separate from the start !) and that would get you till you just buy 5"/54 in late 68 or 71 :cool:. (4" kept for smaller ships and lighter AA)
 
Some PM makes a speech about the RN being 'most calibre' in the world (a misspeak for most prestigious and highest calibre). And the RN misunderstands....:p
 

Ming777

Monthly Donor
I'm thinking its the similar kind of thinking that led to the three Tinclad large cruisers.
 
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