I’m a reinactor and service the muskets for my regiment, what i can honestly tell you is that in the field, i bring home with me (or are mailed) at least 1 Indian musket and or lock with me each time to repair or tune.
At Monmouth a french 1728 from loyalist arms had its stock break at the wrist, clean break through and through from just firing a heavier blank round.
Another french 1728 with a poor performing lock.
Before that two brown bess locks and 1 musket after Brandywine and battle road.
There is virtually no money to be made working on these muskets, which is why many professional builders won’t work on them or if they do, limit their time on them substantially.
i simply do it ensure that arms are maintained for use.
The biggest issue i have found is the locks and stocks being of very poor quality, while i don’t like the way the barrels are breeched, i can’t say they’re not suitable for shooting or re-enacting. But I’m a little more on the picky and conservative side, I’d personally rather have a barrel that is breeched with an appropriate plug