It does happen with moderators. The chance of it doing so on a brake or flash suppressor is very tiny.
But the fact it happens with mods isn't an argument in favour of proofing them, just for gunsmiths to do it properly.
Indeed, the moderator-proofing-propaganda I saw at the Brum proof house when I was there over a decade ago was clearly a photo of a mod wrecked due to a baffle strike and not a pressure failure, a problem which will show itself with a simple test firing with a normal cartridge and doesn't require an action-stressing proof firing...
I am no cheer leader for the proof houses whom I would add to my collection of narrow vested interests! Their various attempts at introducing periodic testing for example cuts no ice with me!
.. but some of the work I have come across had clearly never even been test fired! Part of the problem of course is the lack of suitable ranges and the difficulties of setting up testing facilities! My view is that we should get rid of the centralised proof houses and have a certification scheme for businesses that are equipped and trained to fit and test safety critical parts, however it is in many way a "who will bell the cat" problem, and I have even less trust in the processes that would be needed to set up such a thing.
If the National Firearms Factory can make such a cluster of designing, manufacturing and fielding the L85, what chance is there for the rest of us?