One reason hats got their brims pinned or stitched up on the lock side of the head. Maybe a reason too for the full facial hair going out of style, and coming back just about the time percussion replaced flintlocks in the military world. The few boot-level accounts I have read mention the men's faces being blackened with powder soot after a serious engagement
Remember too that most reenactment group shoot only a loose powder charge, that is not even tamped down. So even their vent jet is pretty minimal. Most I was around tended to over prime since it looked more dramatic. made crowd go oo-oo-oo-oo-oo, and the sponsors happy. At one event my outfit got called on the carpet "the sponsors issued your powder ration, We want to see lots of flash and smoke".