I am not sure why I am reading so many crazy stories and posts about the impossible outcomes of trying to take off the nut on the end of the KSG.
Maybe I was lucky and if so it seems very lucky, but I used a punch and hammer, put the punch in the grove at an angle, and started taping as my friend held down the gun. About 5 minutes of doing this, the nut broke free and I screwed it off.
I re-applied blue lock-tight to the new muzzle break and screw it on. Waited 2 days and went shooting. Shoots great. A must have for the KSG.
Thanks Carlson Comps for making an amazing product.