I don't worry about the "Dirty" much, as you say it will wipe clean. What I do worry about is Black Powder will burn at -50 in a 4,000 psi load, in fact it will ignite easily & burn about as quick in open air as it will under pressure. 800X or any other smokeless "WILL NOT". The Slower the powder the more it is designed by either shape, deterrent or both to slow it down. These also make it harder to ignite. Some double base powders burn dirty because of their Nitro-Glycerine content. If a Single base powder burns dirty it is usually because of incomplete combustion. If this be the case the biggest concern "IS NOT THE DIRT"
