A second mag? Don't think I've ever seen anyone say that before lol. I personally feel that if you only have a couple mags you really don't have any. I can't even count how many AR mags I have at this point, but let's just say when I buy them I purchase them by the 10 pack lol. My favorite as of late has been the MFT 30rd (Mission First Tactical) They run $12 at Cabellas and 10 packs are like $80. Magpul mags are also good, and in the same price range as are many others like Lancers, C Products, Hexmags, Troy, IMI etc. I just bought a few more 20rd Pmags for use while sitting and shooting from a table and I paid $13 each at local shop. (30rd are a bit too long) This day in age everyone and their brother makes AR mags, and generally they all work pretty well and are priced similarly. Stick with larger companies that have the best prices and you'll be fine. Good luck.