Did you buy the AR series RCBS die set? They come in a black box. I have a set of those in .308 and .223/5.56, they are small base dies and i have had zero problems with 2 AR-15's and 1 AR-10. They came strongly recommended from an old timer reloader I ran into at the store who loads religiously for AR's. I'm glad I took his advice, because I feel I saved on money, time and headaches.
Of course I also spent the money on Wilson case Gage's to setup my dies.
Lock and load, the zombies (democrats) are coming (to take your guns)!