The coach gun uses two shells every time the gun is fired, twice as much as the 12 Gauge Pump-Action Shotgun. While high in firepower, the pellets' wide spread makes the weapon ineffective past short range. Unlike the pump-action shotgun, there is a significant amount of time between shots, which greatly decreases the rate of fire. The coach gun's reload animation is significantly shorter in deathmatch mode of the classic Serious Sam titles, giving it about the same delay between shots as the pump shotgun does.
In Serious Sam 3: BFE, the coach gun's shells excel at point blank range however, bullet spread greatly limits mid to long range effectiveness. It behaves exactly like the coach gun from Serious Sam 1; it fires both barrels at once, but the gun is automatically reloaded afterwards. It also has very high recoil, unlike the coach gun from previous games, making it more less reliable for accuracy unless the player is within close range of the target(s).
When using the coach gun, the player should remember that the reloading animation between shots makes them vulnerable, and should be moving or ready to move as soon as the coach gun is fired.
The coach gun is an excellent anti-Kleer weapon. A point-blank shot will always kill a Kleer in one hit. Short range shots have a chance to kill the latter as well, though a few pellets might fly past the Kleer, especially in Serious Sam HD and Serious Sam VR. In these versions, the Kleer has a a hit-box that conforms more in line with its shape than in the original game.
Sirian Werebulls are less of a threat when confronted by the coach gun. Two short-range blasts can kill one, and landing all of the pellets on a Werebull can be easily accomplished due to its size and hit-box. Alternatively, one can fire a rocket or grenade at the Werebull and then finish it off with the coach gun.
The coach gun can also kill a Scythian Witch-Harpy in one shot at close range, in cases such as a Harpy closing in to perform a melee attack. However, the coach gun is only effective on small flocks of Harpies, due to the reloading time between shots leaving the player vulnerable. It is not recommended to be used when encountering a swarm.
The coach gun is an excellent weapon to use against a single or small amount of Kleers. One shot will kill a Kleer if it is close enough to the player when the gun is fired. The same strategy also works on Gnaars.
It also works well as an "emergency" weapon against certain powerful enemies, such as the Scrapjack or the Major Bio-mechanoid. Their large size allows most of the pellets to connect at medium range, which isn't possible with other enemies.
The coach gun is an effective weapon against Hatchling Arachnoids. However, due to their health and hit-box, one shot is not always guaranteed to kill one, even at close range. Alternatively, you can fire a round from the pump shotgun at the Hatchling and then finish it off with the coach gun for an easy kill. To save ammo, the Sledgehammer can also be used.
This weapon is effective against groups of weak enemies, such as Beheaded Rocketeers. The large amount of pellets fired per shot can kill/gib multiple enemies with one shot, which is useful for clearing out a group of weak enemies without using ammo for the M29 Infantry Assault Rifle.
Its large spread makes it ineffective at anything past close range. This makes it ineffective against enemies that prefer to stay at medium or long range, such as the Witch-Bride of Achriman.
The coach gun works great against medium-strength enemies, such as the Methug Soldier or the Hermit Crabuloid. It does enough damage per hit that it can kill a medium strength enemy in two or so shots.
Its reload time is quick enough that it can also be used to take on small groups (2-3) of medium-strength enemies as long as the player is constantly strafing. This makes it handy for taking out groups of medium-enemies if they haven't acquired a rapid-fire weapon, like the Thompson submachine gun, or need to conserve ammo for those weapons.
It is an effective alternative to the rocket launcher for stronger enemies, like the Bladder Beast, if the player is at close quarters and can't use a rapid-fire weapon for various reasons. While each shot does less than a rocket does, it does do a good amount of damage per hit, which is much better than a shot from something like the Schofield Pistol.
Unlike real-life double-barreled shotguns, the coach gun only fires from two barrels when fired, whilst the latter can fire one shot either individually or two shots at once.
The coach gun in Serious Sam: Xbox has a different, slightly improved model compared to the PC version.
The Serious Sam HD version of the coach gun is based on the Xbox model, as opposed to the PC model.
In Serious Sam 3: BFE while sprinting in first-person view, Sam holds the coach gun upwards, while in third person view, he holds it downwards. The reloading animation is also different. The same applies to the pump shotgun.