first what are you talking about powder running to the front?First bumble bee thing is a gross myth that has been going around for some time, it's simply false.
Second this is what is going on when you fire.
4500 frames per second
So please explain 'shut down the fire' when a) the fire source is outside of the cylinder and b) powder in the rear of the cylinder gets ignited and runs to the front.
The fire source is I assume the fired cylinder it spits out all sorts of flaming nasty bits
of black and lead if you dont have grease covering the nearby cyls there is a very small
chance that the nearby cyls could also catch fire (which is generally very very BAD)
the grease prevents this
look like i said test it yourself the grease smothers the fire light a match and stuff it in a pan/pot of lard.
even though lard is flamable chances are the match will be extinguished before the lard
catches fire
well im off to bed after this ill look in on this tomorrow perhaps you will have a chance to test what im saying