Because you didn't break the guns in the turret, you dove in, the men manning the gun saw you, jumped out and ran for it. Your tracers ignited some of the lubricant for the guns, the men ran back into the gun, put out the fire, cranked the turret over and shot you down.
Or, the Wirble was supporting some infantry, the plane dove and killed the gunners, the infantrymen not wanting to die by strafing ran over to the wirble and shot you down.
There's plenty of scenarios to explain the game mechanics.
However, traveling at 400 miles per hour in a P-51 after a dive means you're traveling in excess of a kilometer per second. I'm sorry to say it.. but film or it didn't happen.
At 400 miles per hour you would be out of range of the wirble you had shot in less than 2 seconds. (~1.5 kilometers) 400 MPH = 643.someodd KPH. 600 KPH = 1 KPS
Even going by good reaction times I find it highly unlikely that a wirble driver would be able to:
1: Realize his turret has been hit.
2: Bring up the clipboard in order to enable his mouse to click on supplies.
3: Supplies load, deactivate clipboard.
4: Find the plane that shot at him.
5: Return fire.
Therefore I find it far more likely you were hit by a second wirble, an 88, or a field ack.
