You don't need a revolver, you want a rocket launcher.  And the cold blooded perk.  
  
I'm going to prestige soon, but I want my 500 headshots with the ACR ( I need less than a hundred).  Plus I need another 22 kills with the FMJ attachment.  I wonder which I'll hit first. 
 
  
The magnum is LETHAL when using it Akimbo, and not to shabby by itself either. You can use it as a sniper rifle. 
  
I use the Thumpgun as my backup most of the time, it drives people insane with rage but when you absolutely positively have to lob shots over terrain, its essential.  
  
  
  
p.s 
  
I actually have a positive K/D ratio in MW2 as opposed to COD4. Its way easier to find a gun to suit your playing style in MW2 (I use AUG or ACR) 
 
I'm a bit stuck using the SCAR-H though, but at least it's pretty lethal. I don't think I'll ever use Akimbo with anything else than shotguns, TBH. Not aiming is annoying and I just don't like having bullets rain all over the place.