If we're talking small arms for squads, why not grab some SCAR's? There are several different variants to fill just about any role, designed to be reliable and easily maintained. Plus, using nato standard rounds in both heavy and light variants, shouldn't have too much trouble finding ammo.
Silence-able too, if you really want to kill zombies with minimal noise.
The Zombie Survival Guide was fun to read, but I wouldn't really take everything he wrote to heart (if you were going to take a zombie apocalypse scenario seriously to begin with); his recommendation to use WWII era weapons might make some sense, but it doesn't take into account a lot of problems you might encounter when using something like an M1 or a Mauser.
Easiest way I can compare this to zmod is to compare it to hunting deformed's. Would you grab a scout and hunt them?
"An Air Force A-10 Thunderbolt II flew a show of force and expended flares for emphasis over Salerno after enemy forces attacked a coalition forward base. The arrival of the aircraft prompted an immediate retreat by enemy personnel."