Short Barreled Rifles Built like an AOW...
 

I just posted the following example to try to explane the difference between a receiver registered as an AOW as opposed to a SBR when both weapons were built into a configuration as shown below:

http://quarterbore.com/images/nfa-aow1.jpg

To build an AOW, the receiver must be either a new VIRGIN receiver or an AR-15 pistoil receiver as to make an AOW the receiver must have never had a stock mounted. The AOW is not a rifle, shotgun, or pistol so the Crime Bill does not apply. Therefore the above configuration is legal so long as the weapon as shown never has a stock mounted to it (Then it would be a Short Barreler Rifle)

To build a SBR, a person could register a PREBAN AR-15 lower and register it as a SBR and build a weapon exactly as shown above and it would be legal. If a person was to register a POSTBAN lower (at least at this time) then the weapon could be built like pictured BUT IT COULD NOT HAVE the flash hider! The flash hider on a POST BAN Short Barreled Rifle made as shown above would be an illegal Semiautomatic Assault weapon as defined by the Crime Bill!

Stupid Huh?