In Singleplayer, the magazine holds 7 shells (up to approximately 77 total), loaded individually. It can be found in Hunted,Safehouse, Ultimatum, All In, No Fighting In The War Room, and in Mile High Club.

In Multiplayer, the M1014 has a 4 shell capacity, and is available at rank 31. The M1014 can use either a Red Dot Sightattachment (after killing 25 enemies) or a Foregrip attachment (after killing 50 enemies), which replaces perk 1. The M1014 is also one of the golden weapons.

Arguably the "shotgun of choice" among players, capable of injuring, if not outright killing, an enemy player by expending the entire 4-shell magazine.

However, the M1014 has a number of distinctions likely to preserve game balance. The M1014 has a relatively small ammo capacity (4 shell capacity, compared to the W1200's 7 shell capacity and tied with the R700 for the smallest ammo capacity in the game) and a long reload time. In addition, like the W1200 shotgun, the M1014 will not be able to inflict damage beyond a certain range.

The Steady Aim perk will increase accuracy, but the effect is negligible in close quarters combat. However, the M1014's effectiveness does increase at close to mid-range combat. The regular reload time of the M1014 exposes a defenseless player in the event that the entire four shell magazine fails to kill an enemy or additional enemies appear. The Sleight of Hand perk remedies this by decreasing reload time, reducing player vulnerability with the shotgun.

The M1014 returns in Call of Duty: Modern Warfare 2. It is unlocked at Level 54 in multiplayer. Unlike the Call of Duty 4: Modern Warfare version, this M1014 is classified as a secondary weapon, can accept a silencer, lacks the spare shell holder on the side, and has a flashlight mounted under the barrel which is purely for aesthetic purposes.

Although the M1014 is very powerful and has a high rate of fire, it holds only 4 shells and needs to be reloaded frequently, albeit with a modest reload time. This makes Extended Mags a useful attachment for it, though it only increases its ammo count by 2. Interestingly, if you manage to pull the trigger quickly enough, you can actually shoot 2 shells simultaneously, something not achievable with the Striker. It overall has the best accuracy out of any shotgun in the game (not counting the Akimbo Model 1887s) and makes a decent sidearm for a Sniper class.

When fired quickly, the weapon has decent vertical recoil and some slight, random side-to-side recoil, though this may be purely visual. The weapon resettles back to the original aim point and the grip speeds this settling.

Trivia

• Strangely in game, when the gun's magazine is exhausted and subsequently reloaded, the charging handle on the side is never pulled back to chamber a new round, so in theory the gun shouldn't be able to fire, as there is no shell in the chamber. This is most likely done for balance, as the small magazine is quickly used up and would have a disproportionately long reload time if the charging handle needed to be pulled back. But then again, it may adopt the 4+1/6+1 capacity, and if the single round in the chamber that remains after the gun has been fired was made unusable, its reloading animation would be correct.  
• The US Marine Corps adopted the M1014 in 1999, yet it is the only faction in the game that does not use it. However, one is seen on the back of the Ranger up front on the menu.
• The shells in the shell holder on the side of the receiver are always unused, even when the weapon is out of ammunition.
• The actual shell capacity of the M1014 is 6+1 shells, although the MP version is considered appropriate since it is the M4 Super 90 model, the civilian version, which only holds 4 shells.
• The M1014 and M9 are the only weapons you start out with that the enemy uses (the MP5 is used by enemies, but you start out with it silenced (the MP5SD), which the enemies don't have).
• If the game is set to the French language, the M1014 will be called the "Benelli M4", and when playing in German the M1014 is called "M4".
• In Modern Warfare 2, it's firing sound is the same as that of the SPAS-12.
• As mentioned before, the Extended Magazine in Modern Warfare 2 increases M1014's ammo count to 6 rounds, which is its actual magazine capacity.
• Because each shell is reloaded individually it can take a while before the gun is completely reloaded again. However, you can press the trigger button to stop the reloading in the middle of the reload animation and still use the shells that have already been reloaded.
• When switching to another gun with this weapon, it looks like the player just throws the shotgun over his back.
• In the Museum level in MW2, there is an M1014 with Arctic camo applied to it. You cannot apply a camo on the M1014 in multiplayer.  
• When the M1014 is silenced, for an unknown reason it will get an extremely low Firecap on it.