I've gone through his 2 or 3 times myself, and most of the time using the handgun is a bad idea, as you have like no ammo, just about 15 rounds.
I found using the explosive barrel when a bunch of the zombies were bunched up helped, as it gives you a ton of time, then just simply running around most enemies. But I will pretty much never resort to the knife, that is just asking to take some damage, damage that cannot be afforded.