I am no expert, but I believe there was an internal mechanism that would not allow rounds to be fired if they would strike some other part of the aircraft. I stand to be corrected however.
Yes on all turrets. On some turrets is was really basic and caused the gun to rise up or move sideways so that it could not hit the airframe and on others cut the electric or pneumatic circuit to the gun when pointed at structure.
Thats it for 15 days or so. I am flying to Regina Saskatchewan later this morning and will not be home till 05January. I want to wish each and every one of you guys a very Merry Christmas and I wish good health and happiness to you all in 2025.