Sometimes the FAL short combo device is on very tight. Attempting to remove it using the wrench flats can roll the edges if one does not fabricate a custom, tight-fitting and narrow wrench. This bolt and nut can assist in removing the combo device without damage.
Screw the nut on the bolt. Thread it into the front of the Combo device using the internal blank adapter threads. Snug the nut down against the muzzle device and turn with 3/4″ wrench. Remember it’s LH thread.
Barrel should be clamped as close to the muzzle device as possible. If clamping by the barrel flats, support the muzzle with one hand while turning wrench to prevent bending the barrel.