In Dying Light you will have to work hard for getting any kind of weapon. But it is not impossible, with some logic and smart play you will get the guns in this game quite easily.
Dying Light players assume the role of Kyle Crane (Roger Craig Smith), an undercover operative sent by the GRE to infiltrate the quarantine zone in the fictional city of Harran, based off Brazil, as his mission is to find Kadir "Rais" Sulaiman (Michael Hollick), a rogue GRE agent who has a file that could destroy the reputation of the agency.
But when he arrives, he must choose between completing his mission or helping the other survivors led by Harris Brecken (Stephen Merchant). Watch as the rules that govern civilization crumble to dust. Go through this guide and quickly get hold of many guns in Dying Light.
Side missions
The most easiest way of getting Assault rifles and high class melee weapons in Dying light is to play side missions and kill the bandits. Try to complete more and more missions with Rais' men or bandits, these will give you a heavy supply of guns.
Another way is to keep checking the air supply drops, this can prove to be a rich source of weapons.
Shops
You will have to buy some of the Shot guns from the shop in the beginning. I do not prefer buying any weapon in this manner but, Dying Light offers shot guns only in the shops so far. I will update this guide as soon as I come across another way.
If you have enough cash, guying the guns seem like the only option. Visit these shops occasionally for the arrival of new guns. Do Not forget to be stocked with ammo for your weapons.
Zombies And Patrol Vans
When you kill a zombie, do not hesitate to search it for resources. You will be amazed with how much they have on them. Supplies, weapons, cigarettes, items for crafting and many amusing things.
Another useful location for finding weapons is patrol vans or police vans, if it not as easy as it sounds to go n search a van but with practice I was able to find around 4 guns in 15 vans.