Hi,
in the Book regarding Hartmann the writer did refer to other Pilots, like Rall, who did count as snipers and was able to get kills regulary on 200-500m range. Some of Hartmanns wingis wrote that Hartmann did so as well, but preferred his usual tactic to close in to 30-50m to get the kill for sure.
The preferred tactic of Willi Reschke and his wingis while attacking 4 Mots was to start to shoot only with the MG´s to the tailgunner from around 600m, at around 300m he shifted the aim toward the inner wing or engine and he did enable the MK108 as well.
Pilots did start to dissable the tracerrounds cause they was visible for the target pilot as well, so when the 1st shot wasnt good, the target normaly started to evade.
There are not a few, there are plenty of pilot storys about kills between 200 and 500m.
Since the Brits did use 250yards and the US 300 yards convergence, i would consider this as a normal shootingdistance.
Of course its logical that a closer distance bring much advantage, but not always a pilot could sneak in that close.
Greetíngs,
Knegel