This is not a shooter game. As a result there is not a wide selection of firearms in it. It does not glirify the gun in other words.
Firearm Sourcing
Obtaining firearms is both simple and complicated because (a) they are not intended to be part of the weapon strategy early in game play, and (b) even if you do manage to obtain a variety of them, access to ammunition is not an assured thing.
That said, the following are typical sourcing examples in the game:
Oddly enough it appears that the main means of gaining access to shotguns - which are arguably the preferred weapon when dealing with zombies - is via the Shops scheme. The problem with that of course is that it is a seller's market.
Basically you are exchanging cash for shotguns and ammunition - and cash is not that easy to amass.
While this is not a guaranteed source for firearms, about one in four of these vans will have either a weapon or ammunition in it, so looting any you encounter is a good idea.
You never know when the infected you killed will have a pocket full of bullets or a firearm - though you can be reasonably sure that a uniformed police officer infected will NOT. That said and when it is safe to do so, you should always search the bodies of kills. Just saying.
Guns are basic in this game. There are three types of pistols - all 9mm. There are shotguns, and a couple types of Assault Rifle. There are also some one-off weapons but by and large the point is not to build an arsenal of firearms because using them - when you use them at all - is usually a last resort act of desperation!
Let us be clear on something - when you fire a gun - or use a grenade - it is a siren call to any Virals that are near enough to hear it.
Virals are DANGEROUS. They can climb as well as you can, and they are FAST. The lesson here? You do NOT want to call them to your location.
Bear in mind that if you are contemplating firing a gun even before you pull it out you should be looking around for the closest telephone pole. Because after you fire it to dispatch that bad infested or group of them, you need to immediately (if not sooner) climb that pole so you can sit there and wait for the Virals to get board and leave.
Yes, we are saying that Virals will come. So have a plan to deal with them, right?
You said in The Weapons Overview: "wait for the Virals to get board and leave." That should be "bored" not "board." A board is a plank of wood or you can "board" a ship. Pretty boring huh?
One of the quests at the gas station. You get a police assault rifle
So I am 21 percent through the story(quests)and have not found any other firearms other than two 9mm pistols, so where can I find the shotguns/assault rifle or shops that sell them for cash.