[Antikythera]

Took me about 10 mins with a Hair Dryer and a pair of pliers.

Step 1: Remove Screw from bottom of flash hider.
Step 2: Heat base of flash hider with Hair Dryer.
Step 3: Torque that shit with some pliers.

If you want to keep it intact maybe wrap the flash hider in a clothe and then put the pliers over it.