I guess it must be hard to cut due to differential hardness. I was also wondering how the silver inlay is held in place - is it put in hot or simply hammered into the recess? It would be nice to fill the missing sections, but that might be a technical step too far for my metalwork abilities (at least without risking damage to the barrel).
The silver pattern and the form of the barrel is somewhat similar to this one
http://www.vikingsword.com/vb/showthread.php?t=13706 although this barrel is much nicer. Perhaps mine was a practice piece before he got onto making libra's gun
Chris