AHC: ideal British 1930s/40s artillery, 20mm and above

Polsten 20mm gun. Effective, rugged, cheap as dirt. It got upper hand even over Oerlikon IOTL.

Polsten was a cool gun. One should need the Oerlikon 1st to came out with Polsten? Better make that deal with the Swiss in early 1930s, instead of waiting another half a decade or more.
 
Continuing from 47mm and 3in AT guns, perhaps the next tank/AT gun might be a 84mm type (bore same as with the 18 pdr)? Of course a fully new cannon, firing a 18 lb HE shell, ~20 lb full-bore AP-shot (~2800 fps), and ~10 lb APDS once available (~3800 fps). The HE shell to be fired with reduced charge to save on the gun wear, and to be able to use shells from the 18 pdr. Basically in-between the two German 88 cannon types, power-wise.

Time to go self-propelled :)
 

trurle

Banned
Polsten was a cool gun. One should need the Oerlikon 1st to came out with Polsten? Better make that deal with the Swiss in early 1930s, instead of waiting another half a decade or more.
Yes, i think both Oerlikon and Polsten 20mm guns should have been introduced to British earlier. And yes, Polsten designers learned much on Oerlikon design.
 
The US 4.2 fired a slightly heavier bomb to a slightly longer range and weighed slightly more. I would have the Soviet 107mm (4.2") Mortar it fired a 10kg bomb and weighed roughly the same as the other Allied mortars but had a range of 6,300m
Always thought this would be a good weapon for Airborne, Mountain, Ranger and Marine units.
 
Re, self-propelled pieces. The Crusader AA Mk. I (with 40mm) and Mk.II/III (2 x 20mm) were very good things, but too late to matter. Get the 1-barreled 20 mm on the Vickers light tank by 1939? The Vickers LT should also receive a 47mm for anti-tank use.
The powerful anti-tank gun on M7 chassis, as the what-if model by @Claymore , should've tanken care of anything Germans can throw in. Another take is a a big howitzer (4.5 - 6 in) is installed on the superstructure on the Churchill tank.
 
Continuing from 47mm and 3in AT guns, perhaps the next tank/AT gun might be a 84mm type (bore same as with the 18 pdr)? Of course a fully new cannon, firing a 18 lb HE shell, ~20 lb full-bore AP-shot (~2800 fps), and ~10 lb APDS once available (~3800 fps).

You're understating performance in the L67 version:

The APDS projectile had a muzzle velocity of 1,465 m/s (4,810 ft/s) and could penetrate 30 cm (12 in) of RHA

Should we call the self-propelled version the Charioteer ?
 
You're understating performance in the L67 version:

I certainly would not want to do that.
The 17 pdr full-bore AP shot weighted 17 lbs, fired at 2900 fps - my suggestion is 20 lb fired at 2800 fps. The APDS weighted 7.625 lbs, fired at 3950 fps my suggestion is 10 lbs fired at 3800 fps. Weight of projectile matters with penetration, shot drop and wind drift. link
The 17 pdr was of L55 barrel IIRC.
The bore of 84mm will alow for 18-20-23 lb HE shell, vs. 13.3-15.4 on the 17 pdr.

Should we call the self-propelled version the Charioteer ?

I have no problems with that.
 
I certainly would not want to do that.
The 17 pdr full-bore AP shot weighted 17 lbs, fired at 2900 fps - my suggestion is 20 lb fired at 2800 fps. The APDS weighted 7.625 lbs, fired at 3950 fps my suggestion is 10 lbs fired at 3800 fps. Weight of projectile matters with penetration, shot drop and wind drift. link
The 17 pdr was of L55 barrel IIRC.
The bore of 84mm will alow for 18-20-23 lb HE shell, vs. 13.3-15.4 on the 17 pdr.

You do realise that the British did actually build a 20pdr high velocity gun in OTL?

https://en.wikipedia.org/wiki/Ordnance_QF_20-pounder
 
You do realise that the British did actually build a 20pdr high velocity gun in OTL?

https://en.wikipedia.org/wiki/Ordnance_QF_20-pounder

Of course.
My suggestions would've mean a gun no bigger than 17 pdr or the Soviet 85mm, so it can be instaled on the mass-produced tanks/AFVs of ww2. Don't be deceived about the nominal 84mm calibre of the 20 pounder, it was in the league of the German log 88mm used on Kink Tiger, with accordingly big ammo. Big ammo = less ammo carried, unwieldly for the gunners to use in ww2 turrets.
 
What about heavy artillery pieces? The 5,5 in was a good gun, but I'd stick with 6 in never the less, of course in a new weapon. Or go for 155mm so there is commonality with the French and Americas, the most valuable current and future Allies. Something like the 155mm GPF, but with muzzle brake so it can use lighter carriage and to have less stress on the recoil/recuperator system. Use the carriage for 8 in howitzer, too.
 
Have someone in the Army look at the Bofor's 40mm as soon as it is a viable production gun, get a licence and start making them. Then have some one realise that the new 2lb gun being proposed for both the AT and as a tank gun will use a round not that different from the Bofor's 40mm. Light Bulb moment, chamber the new gun for the Bofor's round, better logistics and greater variety of ammunition for all the guns!!
 
The 5.5 was in a different class to the GPF a different weapon and a different job to do

Job was the same - throw a big shell at a reasonably long range. The GPF will throw it farther by 3 to 5 km, granted it was a heavier piece thus I've suggested muzzle brake so some weight can be shaved. The increase in elevation to 45 deg would've still improve the range of the GPF.
 
As to other artillery - instead of the 3,45" 25-pounder either develop a new 32 pounder in 3.7" calibre, or stick to the 4,5" howitzer. Or develop a new gun in that calibre round. We are taking vehicle drawn and rarely manhandled ordnance here, so whatever you go with will weight 1,5+ tons. IMO a 2 ton 4,5" howitzer is acceptable.
So much a good idea, spin it to the Treasury as a way of saving money with a common platform with the 4.5" Corps Gun, and quietly shelve that one.
The 5.5" Medium Gun did the same job better, especially after the 80lb shell came into service.

And then get some more heavy artillery into service, there is nothing wrong with the 7.2", just develop a purpose built barrel and carriage asap.
 
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