doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com A barrel question for the expert smiths

I don't see how using a micrometer will tell what the wall thickness is on a sxs gun. You can only read maybe 2/3rds of the diameter because of the top and bottom rib.

On my Starrett dial gage I can change tips and go from almost a needle to 3/8" diameter. The contact diameter of the ball bearing on the barrels would probably be in the tenths of thousands, and rotating barrel on gage would give you fluctuations in wall thickness as described by Rookhawk.

I venture to say that most if not all barrels bores are not concentric or even close to outside diameter.

Makes sense to me- as did the article in SSM about how barrels are viewed in Limey-land- and also the proof test- receiver, barrels, forearm group together- clamped in a padded vise, covered by a blast blanket- "good idea there"-- and then at least two "Blue Pills" fired through it-a good read full of useful data indeed-

Rookhawk, the farther up the barrel , from the breech, the better the .018" measurement sounds. Do you remember what the bore measurements were ? Differences in these from the nominal proof and the rest of the barrels might help with the riddle.

The bore diameters were proof stamped as 12 bore. (.729")

The nominal measurement of the bore diameters in both bores were roughly .036" according to my notes. I suspect the gun was backbored because it has a remarkable amount of choke in both barrels that seems inconsistent for a Scott Premier of that era, my own included. Chokes were something like .027" and .038". (approximately, from memory)