Myself, toggunz, ionicdog, spanky, and zack3g, all have them that I know of. Much cheaper than blasting all your 5.56 on Joe Paper.
Definitely get some BDM (Black Dog Machine) mags, ciener kit will need to be worked over about 500 times with some CLP before you shoot it at the range, or you can dremel polish the contact points. Besides that, federal bulk or if you like Mexican food, get some augila SHV, they function flawless but stink.