Welcome to the world of shooting things!!!!
You said you hit the "fake zombie" right between the eyes..... very cool... on zombies, only head shots count... wait until you meet a real zombie.... they are a bit more scary. Bub knows.
Next step.... go visit a gun store with a range.... outdoor is more fun... rent a gun and hire a safety trainer and experience the real thing. Nothing like it in the world. It's addicting.
My buddy has a range and I go there every now and then : My daughter and I bonding with a Chinese SKS :
http://www.youtube.com/watch?v=Pvl6C314TsQ I love shooting all sorts of guns and all sorts of calibers. Trap, skeet, and sporting clays has got to be the most favorite thing in the world. You certainly should experience sporting clays as well..... shotguns, and tiny fast moving clay targets. Most SC ranges will rent guns and sell ammo plus supply a coach/assistant to go through the course with you and give you pointers.... nothing in the world beats seeing that orange clay target turn into an orange puff of dust with a solid hit.
4 for 4 at Deep River Sporting Clays:
http://www.youtube.com/watch?v=-LOrAXwNd1g In Nevada, I'm absolutely certain there are lots of places to shoot and lots of people willing to teach you and show you the little things that make this such an enjoyable sport. I think there is a "full auto" event held there annually where aficionado's from all over bring their machine guns to have fun with other like minded folk. For a price, quite a few will let you shoot their full auto 50 cal and smaller guns. Nothing says "fun" to a "gun nut" like FULL AUTO.
Guns..... an American tradition along with Mom's apple pie. Celebrate freedom.