Unusual Barrel Markings

[Papaorca]

I just bought, today, a byf Luger. I understand the markings on the underside of the barrel except for a line that reads, "C.A.I. ST. ALB. VT." all in upper case lettering. Does anyone on this forum know what this line means?

I purchased the gun as a shooter, as the trigger plate was defaced due to non-matching numbers.