Re the driving springs. We were taught to remove it and replace it safely and were also shown the demo of how it would drive itself into a piece of plywood. We were also taught - and had it drilled into us - to NEVER, ever, not ever leave the driving spring in the breech block. As soon as the breech block was taken out of the gun and before it was put down anywhere, the driving spring was always released and laid out alongside. So said, but inside the tank turrets, it was a simple matter for you or the crew to kick the breech block and allow the dr spring and rod to leap free. Not sure about that but safe working practice and all that.......
Just amazing guns. I have seen them in our old Centurions virtually running all day, hosing down massed figure 11 targets supposed to represent advancing Chinese Infantry