After putting 126 rounds thru my 3" 629 last weekend over a 2 hour period at a farm shoot, (half .44Specials, half full house .44 Magnums)... I'm having the damnedest time getting the soot marks off of the cylinder between the fluting near the cylinder face. I've tried cleaning them off 4 or 5 separate times now with little success. I guess it really doesn't bother me too much but I would hate for the cylinder to be permanently stained because it sticks out on the stainless steel, hahahaha! I've tried tooth brushes and CLP, M-Pro7, and Hoppes oils... I've never put more than 4-5 cylinders full in a session and had little trouble cleaning these spots with the method/oil before! Any suggestions would be welcomed! Thanks in advance!

-Ham