This is not a bug, and it's not a killshooter issue.
Killshooter is, when you hit an enemy and get the damage applied to yourself.
In this case, you were simply too close to the structure (tree) you were hitting. You were getting the fragments & concussion from your own shell exploding into your turret, taking it out. Looking at the film, I saw the round hitting the tree right above your open turret, maybe just 6-8 feet away. A 37mm HE shell exploding right over you crew's head...
This works with every GV and plane. Take a 109K or P-39 and drive it close to a hangar and shoot your cannon at the wall....