.303's

I don't really know about effectiveness of the .303 in real life.

I though don't think it is undermodelled in terms of fire power. If any discrepancy that I'd say that it is overpowered but I am not sure.

Here why I think that it is not undermodelled:

I can make planes catch fire, explode or rip wings off with my 8 machine guns in standard loadout as delivered by CoD. I just made a 109 explode with my Browings online (so standard loadout, no tracers per default of course as I cannot alter the setting right now) and I didn't have to pump several seconds. I at best shot a burst of one second.

I also managed to rip the wing off a 111 with my Spit 1. I frequently set 109s on fire.

If I hit the enemy with the correct distance corresponding to my convergence I do a lot of damage. If I hit something vital it is a quick kill. A very quick kill.

It also depends on the target plane. Some are easier to bring down, some are very robust. I usually have no difficulties in downing a Ju88 but a He111 is more reluctant to fall.

And yes, with the Hurri I manage to be more effective than with the Spit but I do think that it is quite close to reality. The Hurri was reputed to be a very stable shooting platform that is the bullets are more likely to hit home when you aim right than with a Spit because the latter will more make its bullet "rain" around the point you want to shoot at as the Spit is quite nervous. Also I think the gun setup of the Hurri is much better than in the Spit. If I remember well 6 out of the 8 machine guns of the Hurri (perhaps it's all of them) are located very close to each other while in the Spit they are all quite apart from each other. Now if the target is slightly off the convergence point of the guns, the area at which the bullets will hit is more confined for the Hurri than for the Spit and therefore the Hurri will cause more damage in such situations. Therefore I think it is valid that the Hurri overall is the better shooting platform and can cause more damage when the target is not ideally in the convergence of one's guns and usually the target will always be a bit off. So the Hurri wins here.