“A 20mm cannon shell entered....

[Greybeard]

“A 20mm cannon shell entered the top turret, hit the armor plate on back of my seat and exploded, knocking out the left side window and puncturing my eardrum- Only me and the laundress know how close this one came” -Lt. Bill Jewett, flight eng/top turret gunner on a B-17 Flying Fortress https://planehistoria.com/flying-fortress-boeing-b-17-bomber/