Thank you for the kind remarks, it was fun working on a gun sent from so far away. Along with a few guns I've rebuilt from Canada, I can now say I'm international gun smith
....as to the "extractor" marking, looks like old ammo and could be the cause along with a perhaps poor fitted extractor...next time out shooting, load one round by hand with say the center of the date dead top center in the chamber, close bolt and fire, examine spent round and see where the mark is....good luck!