If any of you have ever been in a multiplayer lobby with me, you should know that I exclusively use shotguns. These are guns that most experienced players completely disregard for many reasons, but I question this. I have come up with a guide that will hopefully spread the positives of these guns and overall help with YOUR game. Let's start with a rundown of every shotgun available in Black Ops II.
R-870 MCS: The first shotgun unlocked in Black Ops II. Out of the three regular shotguns (minus the KSG, will talk about that later), it has the highest damage. To counter this, it also has the lowest rate of fire for all shotguns in the game. Because of this, you will most likely want to pick out single targets to deliver a quick one hit kill with. A Suppressor can be hit or miss, basically making it a ranged knife attack. My preferred attachment for the 870 would be the Millimeter Scanner, due to being able to see if the enemy is in one hit kill range before he can see me. This is the last attachment, so the Long Barrel might save your life a few times until you unlock it.
S12: The dark horse of the Shotgun category. As with the 870 and the later M1216, it has a similar effective range, but middle damage. With a consistant (not fast) trigger finger, it can be fired very fast. I commonly view the S12 as more of a close range rifle than a shotgun due to the rate of fire and rifle-like iron sights. My preferred attachment would be the Long Barrel, which this range compared with the rate of fire will cause major flinching issues for the recipeant. The Adjustable Stock can also be of great use, as the S12 seems to be one of the best shotguns for aiming down the sights.
KSG: This gun is everything that a shotgun should NOT be. Instead of firing buckshot as the other three shotguns use, the KSG fires a slug. Basically, this is a single shot that is either hit or miss on the target. Hipfiring the KSG is NOT reccomended, as you do not have any spread to hit the target. This gun though does have the highest range and damage of every shotgun in the game. Viewed this way, it is the best choice for an experienced player. Because aiming is almost always neccesary with the KSG, the Reflex sight is my reccomended attachment. If you want to put a second attachment on, the Laser Sight can possibly save your life at a close encounter with another shotgunner.
M1216: The M1216 is the last Shotgun to be unlocked in Black Ops II. Ironically, it is the first shotgun available to the player, being set up on a good Default class. The rate of fire on the M1216 is automatic, at about the same as the S12 can be fired perfectly. It also has the highest mag capacity in its class, but suffers from a quick rechamber every four shots. A good strategy if your first burst does not kill is to fire about half of the second burst. To avoid only having two shots chambered, use the Fast Mag attachment to quickly get another tube placed on the gun. On the opposite of the previously unlocked KSG, the M1216 is questionably the best shotgun for hipfiring, as it does have the lowest effective range.
Secondary weapon: By now, everybody should know that a shotguns weakness is not firing infinite range hitscans. BUT a handgun is capable of killing at any range, with low recoil depending on the selected secondary. My handgun of choice would either be the Five Seven or the TDI KARD, due to having the lowest recoil. If you have an extra slot to use Overkill, this could come in great use. A longer range gun such as the SMR or the M8A1 will be perfect for getting the occasional long range kill. An experienced shotgunner though will stick to paths that never expose you to long range, as then you could spend this point on say an extra perk.
Reccomended perks: In all honesty, I have only ever used one perk loadout while shotgunning on Black Ops II. As you always want to be moving as a shotgunner, I would reccomend Extreme Conditioning and Lightweight in your Tier 1 and 3 slots respectively. None of the Tier 2 perks seem to greatly effect any of the shotguns, so I cleared this slot. For a third per, either use Perk 1 Greed for Ghost or Perk 3 Greed for Tactical Mask. Ghost is a late unlock that will protect you from UAV's while moving, perfect for navigating behind the enemy. Tactical Mask will make you nearly invincible to Special Grenades, as even a Shock Charge will leave you unphased. Ghost is good if you want the enemy not to rush you, while Tactical Mask is for the suicidal one who wants the enemy to rush their "boomstick".
Tactics: To me, a Shotgun is basically a rushing tool. It has high mobility, high damage, and low range. Use the mobility to get to the enemy before a standard player (Assault rifle mobility) and hit the enemy before they know what happened. For example, rushing down the side of Cargo through the sniper building can usually get me one or two kills on the enemies side of the map within the first fifteen seconds of the game. Another thing you want to watch out for is flanking routes. Use these as much as possible. And example for this would be rushing through the under level of Hijacked to get behind the enemy at any given time. If you need practice at this, just join a game on Turbine with a shotgun and try manuevering without being noticed. With enough skill, an experienced shotgunner will be able to move in high-traffic areas without being noticed, just to deliver one hit kills on unexpecting players.
Shotguns compared to other guns: As stated earlier, shotguns are a completely different breed of gun. The closest comparison in range would have to be Submachine guns. While most players complain that these guns are unbeatable at close range compared to their assault rifles, a Shotgun will nearly ALWAYS beat a submachine gun at close range. The only issue is that you do NOT want to be caught within the "hitmarker range", where a shotgun such as the S12 will get 4-5 hits before you can kill. This will for sure leave you dead against any type of gun. Guns such as Assault Rifles and Light Machine Guns (especially) will be your worst enemy. These guns put down heavy fire that can kill you before you get in range. Decent flanking routes though will allow you to confront these enemies before they see you and not stand a chance at close range. Snipers are more or less a joke to a good shotgunner, as Extreme Conditioning and Lightweight will make you that much harder to hit.
TL,DR: Shotguns are ONLY used at close range, and you have to learn how to always be within this rage. This can be done by using uncommon flanking routes that let you get in the enemies face. Don't be afraid to rush off the start of the game, as most people will not expect this. As far as your load out goes, all of the shotguns are good in their own ways. Use all four to determine which is right for you. A handgun or rifle such as the SMR will aid you in occasional long ranged combat. Use perks that involve mobility, and preferably one defensive perk. Finally, know who you are going against, as that will determine how you have to adjust your play style.
Have fun, test these tips out, and report what happens in the comments section!