As the nitrate content of gunpowder is a strong oxidizer there was never a need for air to aid combustion. The vent was necessary in a flint lock to provide ignition but after the initial ignition no Air was "Drawn In" but rather there was a "Blowing Out" of gases which lowered, not increased, the ballistics of the arm. With guns now having been ignited by percussion for some 200 years I think the "Need" for a vent has been thoroughly De-Bunked. My Isaac Hollis percussion double has no vents or plugs of any type, nor are any needed.
Correct!
