Here's the photo of the crack...
This weekend I had the chance to examine it more closely. The crack cuts through the forward part of the lock bolt hole only. Basically the hole stopped it from moving farther to the rear.
I communicated via email with a few of you who offered suggestions. I'm not sure I fully understand the suggestion about the pin/dowel. Would the pin go along the length of the crack... or perpendicular to it?
I know that, when cutting a slot in leather, you punch 2 holes and cut your slot from hole-to-hole. This prevents the slot cut from continuing to rip. If this is what we're talking about, should I dill out the lock bolt hole slightly larger (since this is where the crack terminates)... glue in a dowel... and re-drill the hole?
If perpendicular to the crack... I could drill at an angle through the lock or breech plug inlet which would hide the repair.