So, started a B42 playthrough and started off in Echo Creek, then came to learn about the Guns Unlimited building and decided to have a crack at it.
Needless to say, my survivor's been picking at this place for 2 weeks, all the while having to deal with absolutely massive amounts of zombies. Started by weeding out the ones in the exterior out to the road & into the field before the building, using molotovs to thin down their numbers.
But now it's gotten to a point where I'm just using my shotgun and gunning them down when I see fit & also using a spare car that's no longer functional to run them down.
What you see now is an area so full of zombie corpses that wearing a gasmask is absolutely required, because the smell's so bad that it can kill me.
What sucks the most: I'm nowhere near done clearing this building out. It's a massive warehouse area that's got a store on the front, but the rest of the building's a rifle range, so the deeper I go, the more I draw out. Because it's a massive building, too, a simple generator's not going to light up the entire building, only one big area at a time. This just adds to the need to wear a respirator, as well as draws more of the hoard out because of the noise.
tl;dr Guns Unlimited is a hellova challenge, but the rewards inside are worth it.