Cranky,
If you have a habit of swapping pellet's, particularly Crosmans with other pellets, you have to remember that Crosman pellets are designed with a much harder alloy than other pellet brands that have thinner skirts. Crosman depends on this harder alloy to make a tight seal using their barrels. In doing this, the Crosman pellets leave behind a lot of antimony and bismouth deposits on the barrel, and it's hell to properly remove it. For this reason, I use a separate barrel for Crosman pellets in my Marauder, will not shoot a Crosman pellet in a barrel that shoots a different pellet well, don't want to foul it and ruin that barrels accuracy. Lubing the Crosman pellets might help, but I wouldn't count on it.
Tom Holland