I clean all my guns as soon as I get home from the range but I haven't cleaned the magazines other than to wipe any gun shot residue off the top. How often should this be done (if at all)? Can not cleaning the magazines lead to problems down the road? The pamphlet that came with my Sigma shows you how to dissassemble the mag but doesn't say anything about cleaning it while the gun instructions are very specific about cleaning and oiling.