Hot water / cold water trick?
 

My 6" War Machine's chain gun is a little bit warped, and I read someone else said to put it in hot water then straighten it out, then dunk it in cold water to harden it back up again.

So I tried it, with water just as hot / cold as my kitchen sink could go and straightened it out, but it went back to normal. So I'm just wondering exactly how hot / cold it needs to be, should I over compensate when bending it the opposite direction... etc. I've never done it before so I'm just not really sure of how to do it. Does it need to go from almost boiling water into ice water? Does it only work if something is warped badly? Because this is pretty subtle but my OCD-ness is getting the better of me and I want to fix it.

Any advice?

I'm don't know too much about this, so I could be wrong, but I believe I'ver heard to boil water.