"What is the purpose of having a vent in your 209 breech plugs even the fixed vents from the factory?

Why isn't the powder allowed to set right on the face of the primer?"


IMHO, The vent Hole / vent liner limits the amount of gas pressure that is forced back to the 209. In the Micro/milli seconds that the load fires and pushes the projectile up the bore, pressure is built in the barrel side of the vent and is above the operational design criteria if a 209 primer.

The vent is an orifice that restricts the passage of gasses going back to the primer side of the orifice. Because the High pressure only lasts Milli seconds, the pressure passing threw this orifice into the flash hole/channel can't rise above the limits that the 209 can contain.

All shot shell primers, hence 209s, are only designed to stand the pressure of "Modern Shot Shells", something much less than the PSI. of a Heavy sub load.