Akins Accelerator district court ruling
Pdf of ruling here. As I understand it, the Akins involves letting the action slide in the stock so that the trigger essentially pushes itself against the finger, firing as fast as the device can cycle. ATF initially ruled that an Akins-equipped firearm was not a Title II since the trigger is pulled once for every shot. Then, after Akins began production, ATF reconsidered and ruled that it was a Title II since once the trigger is first pulled, it will continue firing until it runs out of ammo or you consciously "release" the trigger by moving your finger away. The court rules with ATF's last position.