Thanks, Juha.
That's interesting as the synchronised rate of fire of the UB was supposed to be twice as fast as the M2. The UB's RoF is given as 1,050 rpm free, 800 rpm synchronised, while the M2 managed 800 rpm free and 400-500 synchronised, according to my information.
If only I could gather the information about belts it would make for an interesting study. Nobody pays much attention to them but they were critical to successful performance, and it was important to get the characteristics right; they needed steel of a certain springyness - to use a technical term
- which wasn't always easy to acquire, especially under wartime conditions. The 30mm MK 108 in the Me 262 also suffered from belts being pulled apart under G-forces, as did the 20mm MK12 cannon in the Crusader F8U jet fighter.
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