The screw is a special item, there prone to breaking and then it becomes a real pain to remove the pieces, My old BT-100 always seem to break this screw... Good Luck.... also when putting it back in put some blue loctite on it
Take just the barrel without the wood and spray it with solvent or brake cleaner then blow it off with compressed air. Be sure to oil it lightly before your done. I use G96 Gun Treatment and blow it off with air again but not completely bone dry when I'm done. Taking this screw apart for cleaning is not necessary so leave the screw alone unless something is broken. I have 40 year old BT's that never had the screw out except when I broke an ejector extension on one of them. Use a thin bit screwdriver blade and NEVER put locktite or any other crap on this screw when installing it again or you will have trouble next time.