Yukon
NEVER EVER use a knife to scratch out the Bp ejection charge !!
A hard plastic part maybe . But I would advise not to do it.
I am 61 and in my younger years ( late 60s ) I got the same idea to remove the ejection charge
from a motor and things did not go to well. Luckily I did not have the motor end pointed
in the direction of my face.
What happened was when I was using a hobby knife to scratch out the ejection charge the ejection charge ignited and started the propellant charge to burn backwards from top of motor to nozzle .Before the propellant had completed burning the Estes paper case ruptured and split down the side.
All of this happened while the motor was IN MY HAND !!! The results were a slightly sunburned hand that throbbed for a few hours and stopped . No fingers lost thank god it was a small "C" motor . The only damage was to my pants and drawers !
So please be safe out there sometimes even the simplest things can hurt you ,
Bobby