I've reviewed many of my old America double gun manufacturer's catalogues. I find extra sets of barrels regularly offered in Remington Arms Co., A.H. Fox Gun Co. and Parker Bros. catalogues. Don't see them mentioned in most of my Baker Gun & Forging Co. catalogues and price lists. The one Baker catalogue I have that does mention extra sets of barrels is from the time after the Batavia line had been replaced by the Black Beauty and Black Beauty Special. All this doesn't mean to imply that one couldn't send your Batavia Special back to the factory for an extra set of barrels. I'm sure Baker, like all of our manufacturers, would do whatever the customer was willing to pay for!!
As far as the chamber length, in those days from the 1890s to the mid-1920s most of our double gun manufacturers didn't mark the chamber length on their guns. Actually they often didn't even mark the gauge on the guns!! Chamber length and load data usually only appeared on the hang-tag.
