Mike, what you write is interesting, and imaginative, but i remain unconvinced. My recollection, is the scientist that addressed this issue, wrote that the shape of the vent liner is irrelevant, to the amount of pressure reaching the primer. My inclination is to side with science.

The pressure on the primer increases with increasing flash hole size. The pressure on the primer decreases with increasing flame channel volume. These i believe.

Yes, i believe there are characteristics that affect the pressure on the primer, but the shape of the vent liner is not one of them.