Just a comment; the last time I was at Tip Curtis's shop he had just come back form the woods with a turkey he had killed with a gun he had just built and was trying out. It had the same 38" Colerain turkey choke barrel on it as your fowler.
This was a long time ago but I am pretty sure he showed me the pattern he had shot out of his fowler, at 40 yards the pattern would rival any modern screw in turkey choke.
These barrels were made for one thing; killing turkeys or any other long range bird hunting, not for round ball shooting. I tried to get one back in the day but Colerain stayed sold out of them so I built a 12ga jug choked fowler instead.
