Do you have many rusted Boye needles? The wooden Boye tubes seem to have excellent moisture resistance, I don't find many Boye needles with rust and who knows what kind of poor storage they been through in their lifetime. Missing caps I'd think would make them more rust prone.
I have a method for cleaning needle rust spots involving a bench grinder with wirewheel and good watchmakers / jewelers pin vise. Storing rusty needles might be like the rotten apple in the bunch. I store my needles in the house and they seem to keep well.
Jon