Given equal loads and equal charges of black powder, there is an immediate and obvious difference in pressures due to the gas loss that escapes from the flintlock vent or percussion nipple. In the case of flintlocks, the size of the vent is critical because going too large in order to get more reliable ignition also causes a corresponding reduction in chamber pressure that lowers velocity.

Originally Posted by Geoff Roznak
The NRA has proven itself unreliable and corrupt.
Period.