Taking Down Hunters in Half-Life 2: Episode 2

Here's a quick mini-quide to quickly taking out the evil Hunter robots in Episode 2:

• Revolver -- 3 or 4 shots to the body and down it will go
  
• Shotgun -- 4 to 6 shots at fairly close range (15 feet or less)
  
• Rockets -- 1 rocket, dead on
  
• Vehicle -- slam it with enough velocity and a single hit will take it down.
  
• AR-2 -- use the secondary fire's electric ball for a quick, single-shot take-down. (Note that there is dialog in-game during the last chapter that reveals this if you listen to the entire conversation.) Note that the ball will not bounce off of the Hunter like it does with other targets, so it's one ball per Hunter.
  
• Gravity Gun -- grab an object with the ZPEFM (preferably metal) and hold it between you and the Hunter. Let him fill it with fechettes and then lob it back at him before they activate. (This is hinted at in one of the achievements. Thanks to "GTVc Diemos" for pointing out how to do it.)
  
• Magnusson Device -- Okay, I haven't actually seen these get a kill, since they don't seem to attach to Hunters, but it will knock the Hunter back a fair distance. Just lob it at the Hunter and let him do the rest when he ignites it with his flechettes.
  

I tried the crossbow once on a Hunter, but since it didn't single-shot him and the reload time is slow, I can't recommend using it.