There are two sets of Tactical Carbine DVDs, in which the instructors provide quality info about running your M4gery at peak efficiency.
I know, you think it won't really matter during Zombiggeddon how tacticool your movement, reload, and immediate action drills are. The Walkers aren't going to be doing coordinated movement. That's just half the picture. You need to be on your game in case "fellow" survivors decide the apocalypse means they can throw all the rules of civilization out the window. Not everyone is going to want to play nice with you, Zombie Hunter. That's who these drills are really for.
But you'll also find that proper movement speeds up the kills against the Shambling Hordes too. And really your warm-blooded speed is the most important asset you have against a steady tide of the Undead. Kill them all before they can get to you.