I'm talking about in rush, if you shoot enough rockets as  an engineer at the crates can you destroy them?  What are the ways you can destroy them besides just arming a charge on them?

Collapsing the building, using a good number of C4 charges ( I think about 12), shooting at it with other explosives, shooting at it with a tank. So yes, the engineer rockets would take it down but it would probably be better to just demolish the building. Less cover for the defending team anyways.

Dark_Jon got all the ways I can recall.
 
Usually, if you've got the firepower, you're better of collapsing the building than attacking the objective (providing the building is destructible). There's VERY few structures that can't be taken down with 6 well-placed charges.

You can strap C4 to the objective crate. It does immense damage and in odd cases will bring the building down if it's been damaged enough.

What really C4 does immense damage? Didn't for me... I put 2 charges on a crate and set them off and it took off like 10%

" What really C4 does immense damage? Didn't for me... I put 2 charges on a crate and set them off and it took off like 10% "

" I'm talking about in rush, if you shoot enough rockets..."

A tank with either the reload package or power package can do a decent job of blowing up the MCOM if it pounds at it.
 
Rocket are kind of a 'nothing else works' situation, but they do work.

You can destroy an objective with a KNIFE!!!!!!!!!!!!!!!!!!!! 
 
  

Yes - it takes about 10 direct hits. If your team is made of sackless pussy campers, start spawning as an engineer, get an angle on the M-COM and blast away. Be aware that it will take some time and is a last resort tactic only feasible on about 50% of all M-COMs. If you want a chance at being successful, you got to start with this approach when your team's still got about 25 tickets left or you'll most likely run out of tickets before blowing up the M-COM.

Not sure about RPG rockets, but it can be destroyed with Stationery AT rockets in Val Paraiso map hehe!  Takes around 6 successful shots I think.  I guess it can be destroyed with RPG rockets, but just like the others said, it's not practical since it will take a lot of rockets to destroy it.  I guess a grenade launcher can also destroy an MCOM too hehe!

Yes, it does work. However, the M-COM can take an absolutely ridiculous amount of damage, so this is a pretty useless tactic. If you can't get in to the M-COM, the other alternative is to use Destruction 2.0. Yup, collapsing the building.

Rockets?  Why use rockets?  Equip anti-tank mines, have someone roll assault with you, then stack about 8 or 9 mines on the objective...  ...and light that muthafucker up like it's Christmas.  GAME OVER! "

If I'm an engineer, I throw mines on it. If I'm recon, I strap it with C4.  
 
Someone's bound to throw a 'nade in there after you arm it and leave. The extra insurance is nice.

Anti tank mines are nice because they do not disappear even if you you die. But just like C4 I believe you can only have 6 in the field at a time.
C4 is nice because you can resupply it yourself as a soldier and a full load of 6 upgraded C4s takes out 50%.
Rocket launchers can be viable in a pinch or if it is already damaged, but is usually a sign of desperation, used when you cannot get to the objective at all and only have a firing line.
Tank shelling can be done as a pussy way out. For this you usually need optics and a good aim or at least compensate after the first shots. Can be even done by blind firing but this is hard and rare.
Port Vvaldes first base Bravo is my favorite to take out using an ATV strapped with C4. (if I find my teammates lacking cohones)

There were a few maps in the first bad company that I would just blow a hole in the wall, then sit there sniping the crates with an RPG-7 until it blew up.  Haven't seen an opportunity to do so in the second though.

Yeah but they don't do a lot of damage