I know of four MX10 ribs that have broke in the Denver area alone. All failed in the front notch on the rib. Seems Perazzi did not know about sharp corners on a part that will flex so the bottom area of the notch snaps off. They don't seem to be too big on fixing them, under warranty, either. Seems if the barrels were ported Perazzi says it's not their bad. The new, and replacement ribs have a radius milled into that corner. First time I saw that deal I offed one MX10 o/u and one MX10 combo set. Never liked them anyway.
I thought I might have squeezed it down into my Warrick case and put too much pressure on the rib. Both notches front and rear have snapped off. It is still functional but I want to get it replaced. I have not done anything yet, been too busy at work.