Dear Hive Mind,
I managed to do something today that I have never done or seen before.
I recently built a gearbox for a boneyard rifle that I bought. It is a ZCI gearbox shell with the internals being pretty much what came out of the old gearbox, including the King Arms 18:1 gears. The shimming was very nice and the gun sounded rather good. AOE is also good.
Today, I took it along to a site to test it; at first, all was well. Then, nasty going noises started, ending with the whirring sound of death.
On getting it home, I discovered what is seen in the photo: the spindle of the KA spur gear has sheared.
The gun was running on a 1450mAh 25c 11.1V LiPo driving an M105 spring.
So, Hive Mind, what went wrong?