Placing explosives is the most important thing when it comes to using them, do it wrong and you'll either get a teamkill or end up being killed.

C4:

C4 has the advantage of you being the only thing that can blow it up (except if you place it on a red fuel barrel or vehicle and that blows up) so you dont have to worry about teammates rushing all over it when laying.
Downside is ofcourse that it aint smart enough to blow up when the enemy gets close so you'll have to do it yourself.
A very important thing to know about placing all explosives is that dark spots (not neccesarily shadow) are the best 'open' spot, its very hard to pick out an explosive there, especially if you dont know its there (the enemy wont know, duh) and you're in a moving vehicle.
The best allround spots for C4 are:

The backside of trees
Bushes (the best spot, period)
Patches of grass
Behind the corner of a wall
Just behind an object
Ceilings
Between crates and stuff like that.
High spots.

Ok quick review of those:

Backside of trees:

With the backside I mean the following, if the enemy armor comes from the north, lay it on the south side of the tree and vice versa, very simple and invisible to the enemy vehicle. 2 packs on a tree will kill any vehicle if timed right.

Bushes:

THE perfect spot for any and all C4 packs, its completely covered, you just cant see it at all and these bushes (especially on karkand and sharqi hotel flag) are often in the MIDDLE of the road, making them the ideal spot to lay C4. Again 2 packs is all you need.

Patches of grass:

Grass is also a good spot (mostly on chinese maps) as a vehicle will often see the grass from the front and then the grass covers the C4 pretty well. Laying C4 in a water puddle near grass or a darker grass patch is even better. Great thing about this is that grass is just about everywhere.

Behind a corner:

The most simplistic use of C4, tuck it behind a corner and wait for the front of the enemy's vehicle (or head) to stick out and hit the trigger. Make sure its really at the edge of the corner or the collision settings of the game will stop a large part of the damage radius (line of sight). Dont lay it to far or the enemy will see it easily.

Just behind something:

Bricks, concrete pipes, you name it, its still a good spot, but a large part of the blast radius will often get caught by the same object so you'll have to think about where to lay C4 and where there is going to be damage and where there isnt.

Ceilings:

Another great spot as no-one ever looks up, no-one just does, flags like the hotel karkand flag are great for this. Also think about small ledges and stuff like that.

Between crates:

Mostly used on flags its a great hiding spot and leaves for many openings in the blast radius so you'll still get a lot of kills as the radius often just tends to a small bit of the enemy, which is already enough. Just make sure you tuck it between the crates nicely.

High spots:

Think about overhanging signs, the top of brick walls, lightposts, the backside of flag/telephone poles, stuff like that, again no-one really looks there and its still a great spot to lay a pack.

Other:

Holes in the road are also good spots, just dont lay it to much in the center.
Never lay C4 in the middle of an open road all uncovered and for all to see, the tank will go around it and you wont have a lot of C4 left.

Mines:

Mines are just as easy to hide as C4, but it has a smaller blast radius and only blows up if a vehicles goes over it.
Some of the above named for C4 can be used for mines, but some are not.
The best spot for any mine is a good dark spot in the road or a patch of grass.
A bush might work, but most players generally dont drive over a bush in the middle of a road.
Laying it just around corners works pretty good too, think a lot about where you would go if drove that vehicle.

A good spot for both mines and C4 is the top of a ramp, go all the way to the top of a ramp, when the road levels again, go a little further and lay the mines or packs, often 2 devided properly across the road is all you need. The vehicle's point of view will be a lot higher then normal since its on a ramp and wont be able to see the explosives in time when the vehicles levels out.

Claymores:

The best spot for all claymores are corners! Simply lay a claymore in a corner facing the direction the street is going from which you just turned. (if you run up a street going north and you turned left (east) then lay a pack just around the corner facing west).
Claymores have the same a killradius of 10m which is instant, no damage, just a kill.
Other great spots are patches of grass, forests (lots of trees) and holes or gaps in walls.
Alleys are true kill spots for your claymores.
Laying a claymore on top of a ladder is something we all know now, so dont lay it directly on the ladder, just lay it a little left or right from it and let it face the stairs (90 degree turn). A small object (vent or smoke stack) just in front of the ladder makes even better concealment of your claymore.
Remember, a claymore ONLY blows in the direction you placed it.

Hopes this helps you explosive users out there

Another good way to use the claymores is to effectively use the underbrush. The city section of Sharqui Peninsula is a particularly good place to use claymores effectively. A lot of people like to try and be sneaky and duck around behind buildings and such. If you drop a claymore down a likely avenue of approach, you are almost guaranteed a kill.

Be especially watchful for claymore opprotunities around the City Entranec Flag there. You can place a nice little surprise there between the tree and the wall that is right by the flag (the actuall wall, not the sandbags). Gets 'em everytime.

I gotta get back to work right now, so I'll add some more later on.

So when you drop a claymore...it will blow up if the enemy is coming in the exact same direction in which you placed it? That makes quite a bit of sense why most of mine have failed. Curses!

that and any enemy who passes in front of it. say like on sharqi at tv station. best place for a claymore is on second floor very right hand side between the 2 door ways leading into flag capture balcony in the corner hidden. no one evr sees it and soon as they walk into that 1st doorway boooom dead.

You can also place a nice little claywhore surprise on the ground floor of the TV station as you walk into the stairwell doorway, immediately to the right. Too many people are hell bent on charging up the stairs to check right there for one. Is good times.

yeah I believe that they blow in the direction that you lay them; towards the curved end.

Note the "FRONT TOWARD ENEMY"

The Claymore mine is essentally 1 1/2 pounds of C4 with 700 steel ball bearings in front of it inside of a casing. The curved area is where the ball bearings are at, with the C4 directly behind it. When command detonated (as you have to in real life, none of this drop and forget shit) this is the blast pattern...



In the game, there is a small arming time. I don't know what it is. But I do know that if you deploy one and get killed, it is still active for a short time, I know this for a fact because I got an after the fact kill with one of them. Hope this explains more about the M18 Claymore mine for ya.

arming time is somewhere around 5 seconds, same with the AT mine. and if you stay with sniper kit after your death and you have had placed claymores prior to this death, they will last for a very long time untill you start placing new ones.

Ive had claymores go off 5 minutes later after a death. This is when you will see"yourname"[killed]"hisname" instead of showing [claymore] as the weapon of death.

A correction to my last post about real life claymores being only command detonated. They can be set up to have no user input after setup by the use of trip wires and other covert means of detonation.

very common during the Vietnam war, and I wouldn't doubt other wars too. Just saw a thing about troops in Iraq using silly string to check for trip wires. What a great idea.