reg bottles
I have sucseesfully removed several regs now from PMI bottles, the trick is to get the reg and bottle hot, placeing in front of a blow heater for an hour or so, remove gauges fill nipple and burst discs, it will still need to be clamped in a vice and the use of gator type grips on the bottle, gently does it and you should be fine, once removed clean all threads in the bottle and reg to remove all traces of thread lock. after that should be ok
if your not happy doing this get it sent away to someone that know what they are doing, no one will gurantee safe removal.there is always a chance of damage.