Here is a simple automatic dispenser.

I built a testing range with:
ammo, targets, glassroof & measuring blocks up to 200blocks long.
Go and download it for some fun or build youre own and burn down somting prity.

Story:
I like to check out new redstone inventions and simple gadgets made in minecraft.
But I just got tired of seeing so many bad auto dispensers when they are so easy to build.

Building materials:
1 dispenser
9 blocks (10 for show)
5 red torches
4 redstone dust
1 lever
Use ammo of you're picking, i used Fire Charges.