I'm not sure on that one. I think, and I have no idea on this, if you did that the grease could cause some of the powder to not ignite or cause the flame to go out. Most people either put the grease in front of the ball or put wads between the ball and powder. Another thing is people say that putting the grease in front of the ball also provides lubrication for the bullet.
"It's a gun you loaded on Sunday, and shot all week."
"If God didn't create man equal then Sam Colt had made them equal."
"Fast is fine, but accuracy is everything."