in a way yes you can.....
1. get a bowl of boiling water and drop them in...the outer mass of the barrel will become soft but the core will stay hard as the heat can only penetrate so far.
2. for this you will need a hair dryer...same as above just warm it up and away you go....with this you need to a bit careful not to warm it too much as to make it smell as it can be toxic due to type of resin they are cast in.
personally id go with the water
