what it amazes me is that everybody forgets that only a headshot can bring down a zombie, so the biggest baddest guns may not necessarily apply as almost anything will give you a headshot if you can aim it. btw a shotgun is not a good idea as zombies have a tendency to not walk head to head if you know what i mean.
semp
The SA shotgun is there for when they've gotten too close and surprised you. A USAS12 or something along those lines if I could find it, any tactical shotgun if I couldn't. Aim for the head of the close one, hopefully whatever goes past/around it does some damage to the one behind, or you get a twofer.
The .22LR/Mag is for when you're fortified or making a slow retreat. It would be the one I would be planning on using most often. Just get set up and knock them down around the base of the building. An AR wouldn't be a terrible thing to have, but ammo's significantly heavier than .22. Quick googlage yields weight per 100 rounds of .22LR is 0.75 lbs. Weight per 100 rounds of .223 is ~2.5 lbs. To me, that makes the choice clear.
While blades don't run out of ammo, the operators do get tired. I'm pretty leery of letting them get that close. The flesh eating beetles are an intriguing idea, but I would have to question if they would in fact become zombie flesh eating beetles, as that would indeed be bad.
Wiley.