I tried the heat method, but no success with a regular hair dryer. There are too many points of adhesion and the dryer is not hot enough.

I have a heating device made to soften house paint for removal before applying linseed oil paint. However, it is hot enough to make paint blister and bubble after 15-30 seconds so it would probably melt the finish on the gun.

I had never heard of the freezing method, but will try it. It'll be a zero degrees F freezer though as that is the only thing I have large enough to hold it.