it would be interesting to see, maybe that is one of the many reason's the demons wanted it, becasue after they remade it, I dont think it would work as the door to hell any more.

the knife doesn't work ; i doubt the colt will. it's pretty much the same thing only bullets/a gun instead of the knife =P

Hm. I hadn't thought of that, Simpgirl! Yeah, it probably can't be used to open the Devil's Gate now. But the demons may just want it so they can keep it out of hunter's hands. I don't know. I've just been thinking. We've seen the Colt kill demons and vampires and John said it could kill anything. As far as I can recall, we've only seen Ruby's knife kill demons. Can it kill anything else?

Ummm... out of bullets... Dean used the last one to kill Azazel. Remember?

Dean tried using Ruby's knife to kill Castiel when he was first introduced but it didn't work. So I don't think that the colt would work either.
And no now that its been reassembled I don't think it would open the gate anymore! But its still a good idea, on the demons side, to keep it away from hunters.