If the machine gun is a "registered DEWAT", then it can be legally transferred and reactivated. Registered DEWATs are deactivated machine guns that were brought into the country as war trophies but were rendered inoperable by doing things like plugging barrels, welding bolt faces or chambers, etc. If they are on the registry, they are legally able to be reactivated. In some cases it doesn't take much effort to reactivate one. Ian from Forgotten Weapons did this a couple of years ago with a French Chauchat machine gun.