Hi Sconie,
You need to change the det pin in the chamber first and foremost, which is easily done once stripped down, the the hybrid cartridge is made up of an mgc 5.56 lower shell and inners with a mgc p220 bullet head, this shortens the cartridge enough to work in the commando's magazine.
All of these items are still available, well the mgc p220 cartridge is hard to come by but Tanio Koba make a copy of it that works very well.
Hope this helps
Kickback