The barrel is chilled and the barrel band for the front sight is heated and they are assembled in a fixture on the barrel. When the temperature is stable the sight is there to stay. You can not heat it up to remove it. I have never found a way to heat just the sight enough without also heating the barrel to get one to slide off and I've dried heat sinks, packing the barrel in clay etc
File or mill a slot at 3 and 9 o'clock to where is JUST misses the barrel and pop the band in half with a cold chisel. Even then there will be a tiny bit of compression at the barrel tip. It's slight enough t can be buffed out/off, but it's there.
Most that guys have tried to heat up or some other method tend to end up with a barrel 2" too short that has been recrowned.
RWT