Lee makes two very good tools, one being the hand primer everyone swears by, and the other, the Auto Prime II, which works on top of your press.
Nice thing about the press one, it uses your normal shell holders, so you don't have to buy those extra. Also, if you have something that primes a bit hard, like military .223's that may not have the crimp removed too well, the II will do them fine. Finally, with the leverage you have on the press, you aren't forcing anything, and can feel the primer seat to the bottom of the pocket easily. Kind of like having a bigger hammer, and just tapping...
