Thank for your comments BaronBrown. From my recollection, I thought I did better than that, so I watched in slow-mo:
13:35 Attack from 11 oclock high. Approx 10 hits (cant tell if its 20mm or 8mm) on lead bomber right wing, fuselage and tail.
14:14 Attack from 3 oclock high. 2 hits (cant tell if its 20mm or 8mm) on lead bomber left wing.
16:00 Attack from 10 oclock high. 4 hits (cant tell if its 20mm or 8mm) on lead bomber bombardier position, right wing, and tail fin.
18:33 Attack from 3 oclock high. 4 hits (8mm) on lead right wing and left wing.
19:24 Attack from 1 oclock high. 6 hits (cant tell if its 20mm or 8mm) on number three engine, wing between engine 3,4 (fuel tank?) and engine four and fin. Right wing burst into flame.
Five attacks, 26 hits of either 20mm cannon or 8mm machine gun... mostly machine gun it seems. The trajectory of the 20mm is significantly different, something i'll need to adjust for. It was probably a 20mm landing right in a leaky fuel tank that caused the destruction of one of the bombers.
In WWII, I believe the luftwaffe estimated was that it would take around 20 20mm shells to down a B17.