I recieved the gun I posted the serial number inquiry about. I purchased it on GunBroker and there are many pictures there. The item is listed at:

https://www.gunbroker.com/item/1033299617

I was pleasently surprised by the condition and it looks better than the pictures. It appears to have been refinished at some point but not recently. Absolutely no mechanical issues. It locks up as tightly as a new gun, perfectly on face and shiny bores. Outside of the visible gouge on the side of the stock, there are no serious flaws. The thing that wasn't listed in the ad was that the gun weighs 8 pounds on the nose. The 26" (exactly) do not appear to have been cut and the bores are shiny with no marks. The gun has proof marks consistent with 1855 to 1875 and there is no sign of reproof. The serial number dates the gun to 1871. The barrel inscription gives the 10 Gt. Castle address even thoughScott didn't use this until 1872.

The barrels were marked in the proof house as 11 gauge and measure exactly .759 in both barrels. My suspicion is that they were honed about 8 or 9 thousandth at one time, but there are no reproof marks, so if so it was done outside the UK. I am not certain of the limit; it may be they didn't require reproof, or they may have used the barrels to save weight and bored them that far when made to get closer to a 10 gauge bore. A tight Brownell's gauge shows the chambers to be exactly 2-5/8" but they will accept a new hull to a depth of 2-7/8".

Barrel walls are .15" at 9" in front of the breech, .12" at the 12" and the thinnest section in either barrel is .045". The barrels are a very attractive pattern of laminate.

The gun is an oddity in some respects since as near as I can tell it is a lightweight 10 gauge upland gun (I consider 8 pounds to be light for a 10 gauge double). The address and serial number would indicate that it was numbered in 1871 but finished in 1872. The address would indicate a grade A or B gun, but the engraving, laminate barrels and back action locks would say C grade. The wood however seems better than that.

The final oddity is that the barrel lug where it extends through the frame is engraved with a tiny note that says: USA Patent Nov 1 1870 with no mention of holder or number. The frame is marked as Scott Patent Action and Purdey Patent Bolt. Since this is the year that Scott started establishing a dealer network in the US, I suspect they filed a patent for their action there and this mark is reference to that.

Anyway, this is the lightest, handiest 10 gauge I have ever picked up and I would love to try some light 1 oz loads on doves or quail with it. Years ago I had a Thompson Center TCR that had a 10 gauge barrel that weighed in the 8 pound range and you didn't want to shoot very many full 10 gauge loads a day in it. Shooting dimensions are not modern, but certainly longer and straighter than most classic shotguns.