AA guns + rockets alternatives for 1935-45

[tomo pauk]

Some countries made the greater effort, some were barely scratching the surface, while some other pretty much decided that fighters are the better use of resources. Then we have the USA, the only country that was pretty safe from the air attacks (even if their overseas territories sometimes didn't had that luxury). And thus: what plausible changes and improvements should've been introduced by the firearm-making countries in the specified era to improve their ground-based air defences? Before people say 'make VT fuses' etc, please take into account the conditions of a chosen country.

Mostly about the ground-based stuff, but if you want to add about the naval guns, go ahead.

I'll start with Italy and France: actually introduce a modern 37-40mm AA gun for the Armies, even if it is not the 40mm Bofors.

 

[Shortround6]

This covers a very large field.
The US AA guns range from the BAR mounted on a pedestal for defense of trucks (never saw active service or at least combat) to the 120mm AA gun, over 500 made but only 4 (?)went overseas.

Rockets in general turned out to be a bad deal. Rockets as in unguided. Popular for a short time with the British. Not sure if anybody else did much with them.
Guided missiles took until a number of years after the war to actually become effective.

France ran out of time, and manufacturing capability.
And here we have another split.
Defense of armies in the Field or defense of cities and factories. You actually need different guns for best results.

 

[tomo pauk]

Defense of armies in the Field or defense of cities and factories. You actually need different guns for best results.

Every gun and gunnery is a fair game here
Granted, for the field armies, we'd want something that is reasonably mobile. A number of 80-90mm pices were still good in this, but these are at a limit of what might be considered mobile. If the doctrine is to go with a hit-to-kill (Germans seem to came to that conclusion by late 1944), perhaps a high-powered 75-76mm gun might be a good idea - sorta AA siblings of the 17pdr or the Panther's gun? Trading the shell weight for the better hit probability.

France ran out of time, and manufacturing capability.

French doctrine wrt. what guns they actually want and how many, was also pretty bad. Their new 75mm AA guns were very low-powered for the as far as the AA guns of the 1930s go. The HMG was put down with it's ammo supply system, plus it was much weaker than a half-decent 20mm piece (doh).
I'd start by avoiding the HMG all together, and instead start making the Oerlikons (that the licence is already bought) for the Army needs. Don't bother with 25mm AA gun, better to make a deal with Schneider for their 37mm pieces when it was offered.

For the bigger guns - see what there is that makes about 800 m/s; if higher even better. IOW, take a look at what Navy was/is buying, and piggy-back on that, since there is a host of 75-100 mm guns that fired at reasonably high MV.
Cancel the new weak AA guns.

BTW - Japanese Navy would've been far better served with a good 37-40mm, rather than to rely on the 25mm guns. Ironically, if the French didn't had the 25mm gun in the offer, Japanese might've went with a 37-40mm gun instead...