@RumikoOharaActually, the method to killing zombies with a punch is by shaking the brain. You don't even have to shatter the skull. People get KO'ed when you smack their jaws hard enough because shaking the brain disturbs its functions. People wake up once the brain is able to compensate for the shaking, however, since zombies are technically dead, they no longer have this function.
At best, zombies will be permanently wrecked and twitching on the ground, at worst, they'll be dead.
And yeah, about the range issue: That's why I asked if they could sprint. Kiting them around is an excellent method to deal with slow zombies.