You could just simply deactivate another barrel to exactly the same as that already on your current deactivated Bren (sorry to bore you non Britishicon dewat owners.....). After all, the powers that be have already decreed once that such a barrel is now not a firearm and not capable of discharging a shot, bullet .....blah blah and so on. So what makes the SECOND suitably deactivated barrel any different? In my opinion, that any Court would have to take notice of, that too is incapable fitting into the criteria of a component part.

Just my opinion................