Butlersrangers;
The used Barrel does have the extractor notch, and is definitely a Krag Barrel, with the "P" stamping near threaded end of the Barrel.
The notch I was speaking of in the last post is the standard front sight Notch in the barrel, where the front sight base is mounted/soldiered to. The 03/05 front sight has a band, unlike the original Krag front sight, and my current Barrel was machined down to fit the band accordingly, but as a cut down the factory Front sight notch for the base would not have been there, it would have been lopped off with the front of the barrel prior to attaching the different 03/05 Sight.
By the way, I was unaware the Criteron rear sight mount threads were not the original thread sizes, thanks for the info. ;)