You all know the weapon: The little picture above the shotgun on the unlock tree. The nerfed version of the AR rockets. A miniture APC mortar launcher. The weapon that should have the "Quake" series HUMILIATION sound played whenever someone is killed by it. The silver piece of scrap metal in your hands when someone ghetto-snatches your Voss after you are revived. Whatever you call it, the Clark 12 RDX shotgun can be an excellent asset to both you and your squad. This guide will show you:
1. What a clark 12 RDX shotgun is
2. What damage the clark 12 does
3. How to use a Clark 12 properly
4. How to avoid or kill a clark 12 user:

First, a few of my qualifications for speaking of this gun-
Ingame name- Cpt.B.F.Pi3rc3
Kills with weapon*- 61
Deaths by weapon*- 8
Accuracy with weapon*- 17%

(*= At the point of this post)

All but 3 of my clark 12 kills have come on conquest servers, a good portion of which have come on Tactical Gamer servers. I think I am fairly sucessful because the clark 12 is the unknown- no one uses it, and those who do do so in a maner likely to get themselves killed.

Some basics:
The clark 12 is essentially a grenade lancher. It is used to best effect for indirect fire, or supression. It can also be used to lead enemies into traps. Many of you may believe the clark 12 is a timed sticky explosive, detonating a set amout of time after it attaches to something. This is half true. It is timed, and it is explosive, and it is sticky. However, the timing begins after you launch it. Three seconds from launch it detonates, sticking to something or not. This prevents you from launching it over a 60 degree angle, as past that it will merely detonate in the air, causing no harm and making you look like an idiot.

The clark 12 has the same blast radius as a grenade, but less some damage. It does, at point blank (<1 meter) 80 damage. It does not matter if you are heavy or light armored. At a farther range (1-5 meters) it does 28 damage. From 5-6 meters, it only scares you with 1-2 damage. Of course, this will vary a bit- It sometimes does 50 damage, sometimes 30, it depends on how far you are from the blast. I will now refer to its ammo as "grenades"

Tactics and use:
The clark 12 is one of the most inaccurate weapons in the game. You can aim at a gap in buildings and end up with a grenade at your feet. However, it is similar to a LMG, and as you fire, it becomes more accurate. Therefore, use all four shots at a time, as if you hit something once firing single fire, you probably won't hit it again. Now, if you intend to hit a moving target, aim about 15 meters ahead of him, for the delay between launch and detonation. However, it is better to find some cover near a chokepoint, lay down an ammo box and sentry to watch your back, and open fire over a wall, small building, or downhill. This will create mayhem for forces on the other side, and allow a perfect opening for your squadmates. This is how I get most of my clark 12 kills, mainly at Belgrade (playground and com tower), Gibralatar (Anywhere really), and Cerebre (anywhere). However, special circumstances do come up. In Belgrade, if you happen to see some men in the second story buildings, hide under them, walk out a bit, launch your clip up and reload. (By the way, there are four "grenades" in a clip, much like the upgraded AR rockets) Be aware- IPS shields and small cover will NOT protect you. Due to the Clark 12's RDX properties, its splash damage will go clean around the shield.

More advanced tactics:
This weapon is paired nicely with a LMG or HMG. You can supress you enemy until they hide behind a wall with the MG, then finish them off with the Clark 12. You can do the opposite, and use the clark 12 to draw them into your line of fire. Also, when teamed up with a recon soldier, you can chase anemy infantry with the grenades right into an APM or RDX demopak.

Clark 12 vs Vehicles
Bottom line- Don't bother, unless the vehicle is on fire or you are distracting it. For the fun of it, I included the stats of the clark 12 vs vehicles, if you're interested:

Tanks- 1 damage
APCs- 2 damage
FAVs- 14 damage
Walkers- .5 damage per shot
Walker vent- 2 damage per shot
Rorschs- 12 damage (though they will kill the user in 1 shot)
Gunships/transports- (if you can land a shot) 5 damage
Orange Crates- 1 shot explosion

You vs the Clark 12
A few times I have found myself facing an enemy using a clark 12. Know a few facts
1. If you move out of the enemy's range, and they know what they are doing, they will not pursue.
2. DO NOT lay down somewhere and hide. The enemy has unlimited ammo, and though their shots are not finding you now, they will soon.
3. If you are taking indirect Clark 12 fire, move away from the passage it is coming from, and find a way to flank it
4. If you are low on health, but not too low (like 70 or so) and notice a clark 12 grenade hissing at you feet, there is only on thing that will save you- Jump. It takes you out of the 80 damage area, and may even (if timed right) allow you to take only 25 damage. I do not believe it is bunny hopping because you are doing it to avoid an explosion, much like a grenade, and are not doing it multiple times.
5. Charge the enemy after he has used his four shots. The Clark's long reload time makes him vulnerable at this point.
6. DO NOT EVER run up to a Clark 12 enemy gunman and kill attempt to kill him at close range while he has ammo left. He will launch some at his feet and take you with him.

*Future updates*
In 1.40, the Clark 12's uses are expanding, as it can do the same as RDX, Zeller and the AE diffuser and remove all types of enemy mines. Also, I have heard (not confirmed) that it will do more damage in 1.40 (maybe 100 damage at point blank). I am downloading the 1.40 beta patch as I write this, and will update you with my findings.

FINAL VERDICT:
The clark 12 rdx shotgun, paired with a machine gun, advanced ammo hub, and (choose you favorite) PDS-1/Sentry gun/IPS shield can be an excellent source of distraction for a squad, and can phychologically effect the enemy ("OMG I got killed by Clark 12, Pi3rc3 is h4x0r" [though not on TG]). However, it is sometimes best to leave this slightly underpowered weapon in the armory in favor of the other Support accessories.

6.5/10
It will be interesting to see how well I can use this gun, and how many people will use it, now that this info is out.

Oh sheet mon, didn't know about this thread, did a search and everything. Sorry about any inconvienence to the admins. When I searched, it said that "Clark, Shotgun, and RDX were too commonly used".