[A Strict Constructionist]

And if I remember correctly, most full auto versions fire from and open bolt configuration where semi-auto's use a closed and locked configuration

[elmer fudd]

Most machineguns and subguns do fire with an open bolt, but assault rifles do not. An open bolt is bad for accuracy since you have a very long locktime and the gun is being jostled by the closing of the bolt as you fire. It's my understanding that the BATFE also bans any open bolt guns since they are much easier to convert to full auto.

[MarkL]

And if I remember correctly, most full auto versions fire from and open bolt configuration where semi-auto's use a closed and locked configuration

It's pretty much unheard of in modern rifle calibers, but some pistol caliber full autos will fire from an open bolt.

Mark