I have several Barlings with extraordinarily open draws, one in particular from 1906, a bent billiard, with what was estimated to be a 6-7 mm draw. The carver who gave me that estimate, who is a very well known brilliant carver, was of the opinion that it must have been opened up because he couldn't believe that any carver of the period would have drilled that wide an airway. Problem that that argument is that is that the airway lines up correctly with the bottom of the chamber, and that the airway through the stem is also very open, the widest airway of any of my pipes. I can easily push a pair of fluffies, side by side, through that airway. Every part of that pipe is over scale, massive mortise, massive tenon, thick shank, all supporting a massive airway. Damned thing smokes like a dream.
Like yours, it's a French carved Barling, which means it's very well carved.
Barling draws are open, maybe not as open as some modern artisan pipes, but quite open.
There are always going to be exceptions. I have a small bent from 1921 that has a tighter draft and that's likely because the small scale, narrow curving shank required a smaller airway to navigate the curve while leaving enough surrounding wood. Small tolerances, small airway.
Overall, Barling airflow is quite open. But with the exception of a very few very early, possibly French made, pipes, nothing with that kind of 6-7 mm airway.
