Jim
CTI manufacture a black powder starter pellet for all their Pro motors.
If you use an e-match initiated Pryrodex(R) pellet to start a APCP or hybrid motor, you should inhibit the central bore of the pellet to double the length of the pellet burn and to prevent over pressurization of the motor by making the grain a regressive burner. Here's why.
An uninhibited Pyrodex(R) pellet has about 30 ms burn-time with a neutral burn geometry. Both the inside and outside bores burn so the surface area doesn't change as a function of time. By filling the pellet center with wax, grease or another inhibitor, the burn time is doubled to about 60 ms with a regressive burn geometry. The pellet burns from the outside in and the surface area decreases with time. When inhibited, the pressure generated by the Pyrodex(R) decreases with time as the pressure generated from the motor propellant is increasing. This provides optimum heat transfer to the propellant without over-pressuring the casing.
Bob