Afaik, the Wirbelwind isn't really better than the quad 50cal in terms of damage. When you take a look at the total damage each of these weapons are doing. You will find that the Wirbelwinds gun in a duration of 3 seconds has a rate of fire of 32 and a damage of 3-4 on each bullet. The quad 50cal however has the duration of 3.5-2.5 seconds with a lower rate of fire of 24 but each bullet does 20-15 damage. The Wirbelwind does have better accuracy than the quad 50cal but if the gun isn't doing that much damage it doesn't make much of a difference.
The AA guns feel really weird to me because the quad 20mm is not actually much better than the single 20mm (might even be worse because the single 20mm can somewhat 'reliably' penetrate and damage a Cromwell from the front but I think that's more of a bug involving target tables). And the quad 50cal isn't really that much better than a single 50cal because of how the aim times work. I think the Wirbelwind in particular is really underpowered right now because it's slow, has low maneuverability, and armor not strong enough to deflect 37mm guns. While also taking a long time to kill a single model on a infantry squad because of how the guns stats are set. The saving grace for the Wirbelwind is that the HE mode version of the gun suppresses and pins squads very easily; but I would rather see it do actual damage than be a mobile suppression vehicle.
quad 20 mm is much much worse than single 20 mm... quad is like HMG42 (with ap bullets vs vehicles). The single 20 mm is more similiar to 37 mm Ostwind gun.
The 20 mm guns are the most broken of all, the single as well as the quad.
@all those who still stick with this OP train....
The issue is "bad designed doc", not OP or not. 7 pages and you guys still havent got the point of the debate.