Quote History Quoted:
Wouldn't that last part include a rail tube also? Its for your hand.
View Quote
In 2006 they said if you add anything "extending below the bore/barrel" intended to be used to grip the weapon with a second hand to steady it, you have redesigned it into an unregistered AOW, since pistols were only ever designed and intended to be gripped/fired with one hand. So, that sounds like it should include AFGs, handstops, thumb rests, magwell grips, handguards that have obvious areas for hand placement, etc., since they all extend below the bore/barrel.
Since then, ATF has given their blessing to AFGs and the like, while seeming to stick by their VFG = 90° to the bore definition. According to that, it seems to me that the Hera CQR and the ones below might actually be ok since they aren't 90° and don't meet that definition.*
*I'm not a lawyer and I made a B in geometry.
After all, this is a legal pistol: