I use these:
http://www.cabelas.com/product/Shoot...3Bcat104576580
I have about 40 of the borestores and haven't had any issues. Have been using them for 4-5 years now.
DON'T use socks, Crown Royal bags, or bank change bags. I had a cz52 that started to rust in a change bag. Don't know why, but it did.