I have repaired several broken wrists, as well as several stocks broken at the lock mortise. How folks broke a musket stock at the wrist I don't know...
Cracking through the lock area seems to be from the manufacturerc removing too much internal wood.
Anyway..., I use Brownell's bedding compound. I have used wooden pins set at a 90° angle to the crack. I have also used a flathead wood screw installed into a counter sunk hole from beneath the barrel tang down into the wrist to pull the wood together on a wrist break.
For cracks and breaks at the lock mortise I have used bedding compound, and in one case of chronic breakage, I added wood and bedding compound to the hole for the seer lever inside the lock mortise. For some reason, the machined hole for the seer in that particular Pedersoli Bess was deeper than normal, and the breaks always went through that spot. So.., I took a hardwood disk from the local craft store, reduced its diameter and glued it to the inside of the musket while glueing the rest of the break. I then shortened the seer lever on the lock by a few hundreds of an inch, so it wouldn't bind on the repair piece. Stock hasn't had any problems for the past five years, and is going strong.
LD