The Chain SAW Light Machine Gun has the fastest fire rate but lowest accuracy, range and damage of the light machine guns. You can only fire it from the hip meaning that at long range it will be unlikely you can hit anything. Because the Chain SAW has low mobility and slow handling you need to stay a bit defensive with it. It is good at holding down a position and can take on multiple enemies at once.
The Ameli Light Machine Gun has the second highest accuracy with the highest damage of all the light machine guns. It has fairly high range but a low fire rate and mobility.
The Ameli is best at medium range but also works well at long range and short range if you are prepared for enemies.
The Tac 12 is a pump action shotgun with the most range but lowest fire rate of the shotguns. When you aim down the sights of the Tac 12 your spread is reduced. With the Tac 12 it is possible to complete objectives that only require close range combat. Avoid open areas when you move around the map so that you don’t encounter enemies you can’t shoot.
The MTS-255 Shotgun is a double action shotgun which essentially lets you fire semi automatically. It has the highest fire rate but is average otherwise. The main problem is the small magazine size, you only get 5 slugs between reloads. Move around the map so that you stay in close quarters and always fire from the hip.