Gunsmithing Barrel blank?

[KHOOKS]

I'm looking at a pic of a obermeyer barrel blank. At the chamber end on the outside about 1/4" from the end you can see a blind hole drill end. See http://www.snipershide.com/shooting/showthread.php?t=174286 for the pic. Just wondering what the blind holes is for.

 

[RADcustom]

It is most likely an index mark for the rifleing machine.

 

[colchester]

I think it is a detent for a screw on a lathe dog

 

[Bugholes]

It's an indexing point for the barrel in the rifling machine. Theory is that if the barrel had to come out of the rifler for some reason during the rifling process, it could be reinstalled without loosing its reference. It will turn out when the tenon is turned down