most of that splinter will be removed by the time you finish inletting the lockplate and bolster . not a disaster at all.
That "splinter" is the part that supports the entire upper section of the lock plate, keeping the hammer in alignment with the nipple.
It's not a fatal disaster, but will require considerable thought, little distraction and a steady hand.
Both fractures need to be repaired.
I would use a slow set epoxy, I've had great long lasting results with Devcon 2 ton High Strength epoxy and/or Acraglas.
Acraglas is made for and a proven history with firearms and the Devcon has also proven to me, in our MN seasonal temp swings, to have long term reliability in a few different applications..
Lippy984,
Your going to have to get the epoxy
into the fractures, not just on top. some kind of thin blade like tool to reach/press in there,
(think thin like a wood reed for a musical instrument), then light clamping to hold in position. (inch pounds of torque here)
The repairs will be hidden by the lock/barrel, but they need to be there for support.
Chisels need to be surgical sharp, you should be able to "shave" a piece of wood.
I've done that Pecitonica stock and made a huge error!
It has a different "drop at comb" then the original T/C stock. When I cut the butt to length, I had measured the original and transferred that line to make the cut.
The result was a stock that was too short for a standard length of pull, the project is now only suitable for a smaller gal or youth