It' s gap between the cylinder and forcing cone. Yeah the closer the better but i would leave it alone.
When you say splatter are you talking about the burn ring that develops on the top strap?
if you want to remove the burn rings from your cylinder get you some lead away clothes. takes the burn marks right off. looks new!

Now hog we have got to figure out how to get that 627 across the border so we can make a deal!