I use the same stuff that I use on my pistols and rifles, Ballistol. It works well to keep them from rusting, and it also good on the leather wrapping as well. It also mixes with water and remains a cleaner/oil. So if it was to get damp from condensation for example it would still keep it from rusting.
"Time To reload"
18th IND LT. Artillery
7th IND/ 1st VIR Cavalry
"Are you gonna pull those pistols or whistle Dixie?" Josey Wales
"I've simply been brought up being knocked down" Buster Keaton