Cracked my Italian made 490 in the clamp area the other day. Likely cause - too much clamp pressure (maybe?)

I've always heard that masts are thicker where the boom attaches so I thought I'd saw through and see how much reinforcement is actually there.

Here's the break:


Here's the base thickness:



And here's the clamp area:



I can see that there is an extra layer inside the mast not much more that a sheet of paper in thickness. Re-measuring the wall thickness several times I can see also that the clamp area is indeed thicker, but only just (less than 0.5mm).

What have I learned?
1. Back off on the clamp pressure.
2. Buy RDMs from now on.