This plugin adds guns to the server. Theres different kinds of guns and you can buy them from the black market in-game.
You can even help us by making custom weapons! https://www.spigotmc.org/wiki/how-to-create-new-guns-with-quality-armory/
You can open the crafting window with /qa craft and hovering the mouse over the gun or ammo you want to make will show you what you need. clicking will take the items needed and craft the gun or ammo.