Works with a PaP'ed M14. Get that and the Sliquifier and you are on your way. I just upgraded the M14 and got Speed-Cola and had no problems getting to round 45 (I quit then because it was really late). Going to try again today.
pretty sick if you have a party, if the others die you just finish the round so they revive, otherwise they can run around and unlock and build things while you take the brunt of the zombies.