Originally Posted by
sabotloader
Correct and because of its cone shape facing forward it deflects a lot of the blow back gasses away from the flash hole and back up into the load. IMO - it is the way to go - it reduces the pressure felt on the nose of the primer...
No, me thinks what you wrote is incorrect. Pressure is consistent everywhere, no matter the shape of the vent liner. Gas particles headed toward the flash hole hit the flash hole no matter the shape around the flash hole. Particles not flying toward the flash hole, don't fly up the channel, no matter the shape of the vent liner.
The chemist forum member,
JStanley, showed a drawing of the combustion, in a thread here on this forum a couple three year ago. His drawing showed the gasses of combustion, reaching the primer identically for domed or flat vent liners.