And not to sound like a anti-gun person, but one thing that may have helped the '86 ban be put into place, IMO, was the fact the 2nd admendment was put in place long before automatic weapons were even heard of
Similar arguments to this have been put forth in other threads about machine guns. I can only say that the 2nd Amendment was put in place long before cartridges were heard of as well.
You get into the whole can of worms about what did the founding fathers consider "arms." A musket? A pistol? A cannon? I believe it was unspecified for a reason.