Regular elmers wood glue will take care of it and you can clean up excess with water before it dries.
make sure not to get glue on the mechanisms.
once repaired, if glued well, it should look nearly seamless and be as structurally sound as the day it was made.
If it were mine, I would fire it only when necessary. That gun would most likely hang above my doorway and the shells would be on a shelf nearby.