Ha! That's a hoot. I managed to get up to 95 on my third try. Another tip is to go ahead and fire off any remaining shots when there is a lull so you can reload and have all 6 ready to go once they start rising to eat your braaaaains again.
Wow. It turns out the zombie shooting genre is quite widespread on the web. This one's kinda fun too. The zombies are harder to kill and you can strategize on how to maintain your compound during the daylight hours.