1. Make sure your flash-hider is properly mounted and will not come loose. Do not use loctite, use either a crush or peel washer, or mount the FH directly to the barrel shoulder using torque only. If you use a washer, make sure the HALO collar does not get caught on it and get crooked.

2. As you screw the HALO into its collar, hold the collar in a fixed position and spin the can into it. I have found this easier. When it is just about to get tight, align the halo "U" channel in a fixed position to help retain zero. For final tightening, turn the collar while holding the can stationary.

I have NEVER had the HALO come loose doing this.