what gauge is this parker bro. 1901?

[Lucas Hill]

thanks for that info, and what do you mean by interesting? a full picture of my parker is in the middle of this pic.

[ArtS]

With that size and weight, it is consistent with 10 gauge specs. Maybe bought as a trap gun or waterfowl gun? Be interesting to see what the stock book said.
It would be nice to find a set of 10 gauge barrels that fit too.