We've all tested out the riot shield and decided whether it was a good investment as a primary weapon or not. Most say no, they've been cheated by the shield after taking a killing blow from a bullet  through their supposed defense. While, I must agree, that seems to be a problem with either the game itself or the lag from the multiplayer that Infinity Ward needs to address with a patch. However riot shields have much more practical uses and many players just don't know how to properly utilize it to its fullest value.

     First I'll start basic, yes, you are supposed to crouch with the riot shield to protect your feet, and yes it does protect you from bullets. Great, then why do you still get mowed down by someone's machine gun fire? Because players are smart and they know how to adapt by simply strafing or tossing a nice little grenade or "noob tube" your way. But the user of the riot shield needs to be smarter.

    While using the riot shield there are three things to keep in mind constantly:

I) It is not a combat weapon, it is a support tool.

II) Users of it must always be on their toes to try and outsmart their opponents, brute force simply will not work. A riot shield is a thinker's weapon.

III) Never assume you're invincible. If a sniper is  attempting to snipe you but can't do it, do not attempt to tea bag in front of him as a taunt. He will shoot at you and that death you can't really blame on your riot shield (its surprising how often I hear that)

IV) Look down slightly rather than straight ahead, this will protect your feet so you aren't "Toe sniped"

     These things are key but how does it apply? Well since it is a support tool, do not expect to get the most kills. If you play team deathmatch and generally like to work alone without the help of his team  it is unlikely that a Riot Shield is for you. Team play is crucial, you are the distraction, for example (this is one of the few examples i have in team deathmatch, since I mostly play Hardcore Search and Destroy) in wasteland help your buddies, soak up those sentry gun rounds so your team can waltz in and take out the opposing forces and hold that crucial structure down.  For search and destroy (or demolition I suppose), imagine you have the bomb. think about where the most likely place for an enemy is to appear from  and face the opposite direction and look up. this will completely protect your backside from all but most explosions and  flash/stun grenades can't force your back to lower the shield, because, well, its on your back; and if you have teammates nearby have them watch also watch your back and then the second most likely place for an enemy to come and third place and so on. Most  people make the error of laying down with the riot shield and it just isn't as effective for defensive purposes when completing objectives.

     I said that Riot Shields are primarily a tool, a tool for defense and team work. yet it does have applications in combat.  It is easy to corner someone attempting to kill you, but unless you're playing hardcore, melee isn't the best option since your opponenet could easily strafe and counter with a knife. Instead, consider the throwing knife.  Seeing a person wielding a riot shield creep toward you is a terrifying sight when their spray tactics aren't working, this is the supreme advantage of the riot shield in terms of combat. while the enemy is spraying you should be thinking, "when can I get this guy off balance?" and here's the answer: when he's reloading or when he is cooking a grenade to kill you. This is the perfect chance for the last thing he is going to expect: a throwing knife in his face. 95% of the time (unless I miss which is pretty rare) the throwing knife scare tactic works. Alternatives include semtex, which would be more effective against a group, but alas, is only a one time use unless you have the scavenger perk on.

    Never assume you're invincible with the riot shield. Peek around corners with it on to detect where snipers and campers can be found hiding, if one happens to be turning the corner as the same time as you, back away STRAIGHT BACK, because strafing reveals your sides and are thus vulnerable to attack, but if your enemy strafes, turn with him, protect yourself. the only time this will not apply is in hardcore, where one melee attack will kill and that is acceptable. Otherwise, keep your distance and follow up with the throwing knife/semtex maneuver as I've previously stated.  The most often time that I have been killed is when being snuck up from behind which simply cannot be avoided no matter what your class loadout is, and turning corners. Why? I trade weapons at the wrong time. NEVER trade weapons while moving or turning a corner unless you know for a fact, that it is safe. instead, if for whatever reason you would decide to turn the corner with your secondary weapon, stand somewhere where people are unlikely to see you i.e. a lonely corner, or behind some boxes and then turn that corner. I have a good example of this: once while playing S&D I was at Highrise and turned was in that hallway right under the helicopter, and turned the corner with my riot shield and and the last guy was camping on top of that small building in front of his spawn. He took a few shots and I backed up to safety, in the meantime, he was cooking a grenade expecting me to sit with my shield and just wait. Predicting this and knowing I wasn't safe from him with my shield, i hid behind the nearby crates, pulled out my handy revolver, turned that corner, (knowing it was safe of course) and shot him in the face right where he laid. When up against another riot shielder in close combat, you have two options A) lure him away and toward a fellow teamate and B) kill him.  it is likely that he is going to attempt to strafe around you and either melee or pull out his secondary weapon, this can be avoided with a stun grenade and a quickdraw of your secondary weapon, usually.  If you are of equal skill it may just be a matter of luck, however, it is possible to try and confuse him. i.e. strafe right then left just to throw him off. Using that to your advantage you can come up for a melee kill or throwing knife kill since when a riot shielder strafes, he turns his body in such a way  that it exposes him on one side.

Also, there are those players who will attempt to charge you and melee your back.  This is the supposed 'easy' way to defeat a Riot Shield user for close encounters.  If you happen to encounter such a player, there's an easy way to counter it.  A Handgun should be equipped, since you can pull it out pretty fast, and Akimbo Handguns are most effective for this.  First, a player will charge at you and attempt to flank you faster than you can turn around.  While the player is running at you, immediately pull out your Handgun and fire away without aiming down the sights.  The Riot Shield user will most likely win and come out alive with the melee'er surprised and defeated.

With all of this a question comes up, "what are the best perks to use?" personally, I say it all depends on your style of play. If you are hell-bent on melee, go ahead and go with commando. People would would rather spring to crucial checkpoints and draw fire, should definitely go with marathon and lightweight. However I have a couple of loadouts which I personally deem suitable for riot shield use.

I) Long/Medium Range

 Secondary: any handgun, or M93 Raffica for medium to long range effectiveness

 Equipment: Throwing Knife

 Perk 1: Sleight of hand

 Perk 2: Cold Blooded (riot shields rarely defend one from arial support)

 Perk 3: Last Stand

II) Short Range/Defender

 Secondary: any preffered shotgun (foregrip recommended) or any preffered machine pistol

 Equipment: Throwing Knife/C4/Claymore

 Perk 1: Sleight of hand

 Perk 2: Cold Blooded (More Difficult to be detected thus decreasing chance of grenade spam)/Stopping Power

 Perk 3: Scrambler/Steady Aim/Commando/Ninja

III) Team Player/Survivor

 Secondary: any preference (riot shield will be primarily used due to team reliance)

 Equipment: Semtex/Frag Grenade/Blast Shield

 Perk 1: Scavenger

 Perk 2: Danger Close

 Perk 3: SitRep (early warnings for you and your team)/Last Stand (because nobody gets away with killing you)

     Of course no tool is without its flaw, that is just the balancing of the game, but before anyone can say "I simply don't like the riot shield", give these suggestions a shot. They always work for me