I was also getting some odd cannon action today.
Dove at 520-ish mph after a mossie, in the dive he lost his ailerons, I lost nothing. On the first loop pass, I overshot, looped around, and nailed him once with P-39Q 37mm cannon shell:
Damage after that hit:
Rolled up and over and made a third pass, hitting again with 37mm:
Damage after that hit:
After that, I made a final pass, pinged him with .50cal, then he scraped the ground and slid to a stop, got the ditch, so no kill for me.