Spending Day with BoB Spitfire Pilot - Questions Please

[Upthair]

My questions are not necessarily related to BOB.

1. During the war, did he have opportunities to sneak up behind German fighters and shoot them down? If yes, what was the shortest range at which he fired from behind an enemy?

2. What was the usual ammo loadout of the Hispano cannon on Spitfire Mk V and IX? (I want to know to what extent the HET-AP-HE-AP* sequence of the Hispano in IL-2 1946 is correct.) Between ground attack sorties and pure air combat sorties, was there any difference in the choice of ammo for Hispanos on the Spitfire?

Thanks for the chance to ask a WWII pilot!

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*
HE: high explosive
AP: armor piercing
HET: high explosive tracer