Using a BP booster motor for dual deployment ejection

Living in the swamps of Southeastern Georgia (the one in the Western
Hemisphere) has its advantages, but
also some drawbacks. Such as, I am having a really hard time finding an
online merchant willing to sell me
just a single pound of FFFF black powder.
Staring out the window at an absolutely perfect day to fly
butI'mstuckatworktilldarktoday, my thoughts
(naturally) wandered to the L1 4inch Mosquito under construction, and how to
dual-deploy absent FFFF
grains. Then I realized (Doh !) I've got *lots* of black powder in my
flight box right now, carefully wrapped
in cardboard and marked with numbers ranging from 1/4A through E6.
My question is, why can't I just use a Quest or Estes booster to deploy the
parachute ? I'm using the sustainer's
ejection charge to pop the rocket apart at apogee (still haven't decided on
whether to use a streamer there) so
I need a way to push out the chute at a lower altitude. Acknowledging that
a bp booster won't generate gas as
quickly as loose powder grains, can I compensate by selecting a booster
with, say, twice as much bp in total
as the ejection charge calculator calls for ?
John (posting during lunch when I should be reading RMR)