Original bore?
 

What would be a correct, original bore diameter for a 1901 12 ga. GH with damascus barrels. I know the older 10s were a different bore than "modern", were 12s also different from modern dimensions? Any help appreciated!

Yes, older 12s were larger than nominal dimensions. However, I think that a 1901 12 gauge gun would be the nominal .729 or .730 when factory original. Someone please correct me if I am mistaken.

I think you’re right Bill.





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My Father's 1902 vintage 2-frame VH has bores of .728"/.729". My 1889 vintage GH has bores of .757" but it was back to the Brothers P. at some point as it has the 1910 bolt and bolt plate.

The larger bores were common in the mid 1890's and I don't know when the switch to nominal 12 gauge bores happened. I have a 1901 gun that has .729 bores.

Steel barrels or Damascus? Or would it matter? I was pretty sure the typical sizes of bores changed right at or before the turn of the century.
I ask because I have what I hope is a "cream puff" GH Damascus on it's way to Texas. Very nice wood, nice barrels (outside), sharp engraving and a bit of case color left, overall a nice gun that's been in a family for many years. I have 3 big concerns.....barrels, barrels, and barrels. Numbers match but is not listed in the serialization book. I have agreed with the seller the deal swings on the barrels being good dimension, thickness and shootable condition to MY satisfaction. A session with measuring tools and borescope when it arrives for a verdict. Thanks All!

Austin Hogan published data on this a long time ago. As with most of his research (choke shapes, french polish, etc.) it was so informative that I copied it to my Parker files so that it survived to my posterity. I am attaching it. Bottom line is prior to s/n 70,000, 12 ga bores were commonly in the .755 range, while afterward they tended to conform to the .730 range. Enjoy

In the 1886 Chamberlin Cartridge Co. ammunition catalog they offered special cartridges for Parker Bros. guns with over-size wads.

There is a section in TPS that states the "true bore" was adopted as a standard in March 1892 for 12 gauge. The similar change for 10 bore was stated to have changed a few monts later. The passage states that after that date, a 12 gauge with the oversized barrels would be stamped with an "O", presumably for old or oversized.