The Bofors are the early models, built in Sweden, but also under license in the USP. It was just shipped to Britain for installment.
There were no early models of the Bofors. The M1936 was the very first model produced by the factory.
The 20mm Oerlikons are the early models that were deemed to have a low muzzle velocity. These aren't the fully developed versions that served during the war.
I suppose that's an option,but why you'd want an expensive, slow firing, temperamental gun where the spares have to be custom fitted to each is beyond me.
The USP wanted to have the ability to perform surface battles and AA battles at the same time. The 4" guns were chosen as the primary weapons so that they could theoretically perform either task as needed. The 3" gun was included in all destroyers and in order to provide a dedicated heavy AA armament for moments that involve both surface and anti-aircraft warfare (Still learning from some lessons for Jutland, but mainly Billy Mitchell's bombing run against the Ostfriesland).
Thing is, you don't have any AA directors so your chances of hitting an aircraft without the aid of tracer fire is somewhere between slim and non-existent.
It was developed independently from the USP's allies, mainly due to the fact that USP destroyers were designed to have a chance against cruisers, bringing them into more direct gun battles than their foreign counterparts. In other words, since the 4" guns were not always going to be completely focused on the air, the USP wanted a similar weapon that would fend of aircraft when the 4" could not.
No amount of 4" guns is going to give you a chance against a cruiser, especially not when they're residing in an egg-shell.
Personally, I'd fit her with British QF 2 pounders. A single on each side and a twin in place of the 3". (I'm not sure if they made a twin, but it's hardly a stretch to say that they did, or you could develop one locally)
The Oerlikons could be replaced with single or twin mounted 0.5" MGs or, if it absolutely positively has to be 20mm guns, the Danish Rifle Syndicate had just begun producing the 20mm Madsen MG which, while in inferior to the 20mm Oerlikon M1939, it was significantly better than the M1934.
“Close” only counts with horseshoes, hand grenades, and tactical nuclear weapons.
That which does not kill me has made a grave tactical error
Source Materiel is always welcome.