They are a monocore. They are also one of the quieter cans we tested and sold. Aside from the FRP, they are a good can.
If it is being difficult you might have some lead or carbon build up keeping it from coming apart.
Try soaking it in penetrating oil overnight and see if that helps.
If it is their stainless can, a quick dunk in CLR might help. If its an aluminum can, you are stuck with something like Kroil.
The endcap with the serial number stays attached to the tube. The other end with the deeper and more aggressive knurling is the end you want to twist off.
I put some blue locktite on the serial number end cap to keep it all together and antiseize on the other end to help it come apart.
