What is the most effective way to destroy an MCOM in Bad Company 2 with C4?
Individual or Grouped
The damage you do is simply a function of the number of C4 you set off, whether you set them off individually or in groups.
Count
In his excellent analysis of BFBC2 damage, Den Kirkson analyzed the code and found that C4 does 290 damage at 0-1 meters, and then does a linear drop-off to zero damage at 8 meters. (A human without body armor in the game has 100 hit points, a tank has 1250.)
Kirkson doesn't document, and I don't know, exactly how much health an MCOM station has. But it takes 12 C4 to take out an MCOM station, so the health is somewhere in the neighborhood of 3400.
Which is a lot.
MCOM Collapse
Because of the MCOM's massive health, it's always better to take out a station indirectly by taking out the building when possible. This guide gives details on how many C4 it takes and where to place them on some of the Rush buildings. It takes much less C4 than taking out the MCOM directly.
Placement
It's fine to place your C4 within 1 meter of the MCOM, but be sure no indestructible obstructions will interfere with the blast radius.
Personally, I like putting them on the ceiling since enemies are least likely to look there when running in to disarm the MCOM.
Sequence
- Place the C4
- Arm the MCOM
- Run and hide
- Toss a motion sensor if you have one
- When enemies come to disarm the MCOM, detonate
I used to arm the MCOM before setting the C4. That was... um... a really bad idea. Gives people extra time to find you before you hide. Don't do that.
Loadout
People often think of C4 as a recon thing, but if you want to be a C4 thug you should really play assault and use one of the "all classes" weapons, which will let you pick C4 as your add-on. Your ammo crate gives you an unlimited supply of C4.
Regardless of which kit you play, if you take the explosives perk you'll be able to carry 6 C4 at once, enough to take out many buildings without re-arming.
Out of Bounds
One favorite tactic of... certain people... is to have a friend load up a UAV with C4 and pilot it right to the enemy's MCOM. Do this a couple of times and you can take out the station with no risk.
Except for the risk of getting cursed out, kicked, or even banned, because it's an incredibly lame tactic.
So don't do that.
Use Mines Instead
The engineer's mines have the advantage of staying around and active after his death. A recent poll in the BFBC2 forums shows support for this method.
I would suggest planting as many as possible before triggering them. Your chances of dying before re-planting are high, so you may not get a chance to re-plant. Also, if you die while planting C4, your C4 will stay there, and your team or the enemy may set off your C4, which will still give you points for MCOM damage and any resulting enemy deaths.
It is very common for your C4 to be triggered even after your death since the other team will usually attack their own MCOM's position with explosives, such as grenades or Gustavs, which are guaranteed to set off your charges. To summarize: plant all you can when you have the chance, and your work is done. If you get to press the button that makes everything go BOOM, view that as a bonus for a job well done.
I don't believe there are any disadvantages, damage-wise, to hitting an MCOM with multiple explosives at once. Explosive damage seems to be a fixed amount, and neither degrade nor enhance the effectiveness of concurrent explosions.
From my experience, the proximity of the C4 to the MCOM does matter (and this seems to confirm my position). If the C4 packs are placed more than 1 meter away from the target, the damage will begin to decrease. So, if you place them within 1 meter around the MCOM in all directions, you are more likely to kill enemies when they go off, but you should generally avoid putting them too far away, since damaging the MCOM is a priority over getting kills. The one exception to this would be if the MCOM is within a house; you may be able to take down the house with only a few packs of C4, which will destroy the MCOM in one shot. More details on destroying buildings with C4 are here.