Guns are the primary weaponry that your character will most likely get their hands on. There are a multitude of gun types that use same, different, or shared ammo.
This is the most common weapon type in the game, the most common assault rifle group would be the Stanag group. (Named by the type of ammunition that the guns use) These weapons are for medium ranged combat and can be single, multi-round burst, or fully automatic.
The shotgun group is slightly restricted compared to assault rifles in terms of variety and are much more sparse to find than most weapons. Shotguns can be the most powerful weapons in the game if used correctly, as they have a bullet spread (effectiveness depending on the gun) and can take out one, if not multiple people. Shotguns have a variety of ammo choices, yet all shotguns can only use one specific type of ammunition, such as slugs, 12-gauge, or 12-gauge drum magazines. Shotguns are used for close ranged combat and are extremely ineffective at medium to long range combat, therefore making it a very restricted weapon. Shotguns aren't commonly used because of their lack of range and general ammunition capacity.
Possibly the most rare type of gun, the sniper is designed for long range, concealed shooting. They are very sparsely spread across the map. Snipers are usually slow firing and loud but extremely powerful. Because of their slow firing rate, every shot must hit or else you won't have time to shoot again before your target runs. Most snipers have a smaller mag and have a scope included. They have high recoil, so recoil reducing attachments are suggested. Snipers are not often used in short-medium ranges. One will usually not notice a sniper before the shot is fired.