TwiceBarrel, I did find that an 8 ga. bore is .835. I'm guessing that .035 would be close to full choke and would leave .800 at muzzle end. This is what Bill (eightbore) is talking about, and I'm sure your gun would have that.
10 ga. bore .775, take bore back 3", past taper leading to choke, difference is .060 total diameter, or half that reading on wall thickness and I'm still sure yours has more than .030 wall thickness.
I did see in an old catalog of 1889, the loads for 10 ga. field load were 5 drams of powder and 1 1/4 oz of shot. I don't have any data on 8 ga. loads, but I think it is not much more than that. Chambers were 2 7/8" and I could be wrong but I think the 8 ga. was 3".
If you go to this site, maybe you can get some information from Mr. Liberati on chamber size and chokes.
http://www.10gauge.com/home.htmlRJM, if your friend's gun is a Syracuse 12 ga, with 16 ga bores, I think it is the one that has been rebarreled for 16 ga. Syracuse never offered a 16 ga. and the Hunter Bros. came out with a 16 in 1898.
