I have had excellent results with KG 9 leather kote for leather holsters and mag pouches. You put some on your finger and rub it on the inside of the holster or mag pouch where the metal surfaces touch the leather. It is the only product that I know of that really works. One treatment lasts for years. Brownells has it :
BROWNELLS : World's Largest Supplier of Firearm Accessories, Gun Parts and Gunsmithing Tools
If the link doesn't work go to the Brownells website and put " leather kote " in the search box.