Now, until crazybushman identifies as being in a jurisdiction that allows civilian manufacture of machine guns, we will discuss legalities.
OK, the poster apparently is in New Zealand.
If I read correctly, a Form 1 to make a machinegun can be approved after May 19, 1986 with a proper Federal Firearms License and class II Special Occupational Taxpayer staus, Title II manufacturers' or Class III dealers' demonstration samples, the only new machine guns outside military or law enforcement, and not for an ordinary citizen on Form 1 make and register or Form 4 transfer registration.
How many crimes with registered machineguns were committed 1934-1986 with legally registered machine guns to justify the freeze on new civilian registrations (Form 4 transfer) and ban on new civilian machinegun builds (Form 1 make and register) by the 19 May 1986 Hughes Amendment? One? By a corrupt police officer with access to other weapons anyway?
Given a strict regulation of civilian machine guns that appeared to be working, Hughes went for a ban. We should never forget. With a strict regulation, the antis went for a ban as soon as possible, with no real justification.