If you store your guns in a hard case vs. a safe

Been using the same bags for 13 years with no issues:

http://norustbags.net/

Ran out of room in the wide body safe, and didn't want to buy another.  If you buy $100 or more you can even get a discount.  If they brown or harden they are no longer good.  Incredible investment considering they are rated for five years.  For scoped rifles I purchased the 12" x 52" (6 mil) bags.  About 60 of them back in the day.