This is cut and pasted from a post I made on GT:
I thought I would share my experiance because I am sure many will be doing this soon.
It started by me trying to find out how the thing was actually attached to my rifle. I figured I could heat it up and wrench it off because I thought it was silver soldered in place, but I was wrong.
I went to AR15.com, posted a picture, and asked how these things were put on to make sure, and I got a reply as follows:
Originally Posted By Troy:
It is not silver soldered on. Instead, a hole was drilled into the brake down between the threads, and a steel pin was then inserted into the hole. The pin was welded over, and then the brake was turned to clean up to weld, then refinished. You can usually find the location of the pin and, using a Dremel with a cut-off wheel, grind away on the brake until you can get the pin out. At that point, you unscrew the brake.
-Troy
So, I figured, easy enough... WRONG!
To start, I noticed that the finish wasn't quite "perfect" on the underside of the brake. It was not one of the flat sides, it was the fat, rounded side, so I figured I'd start there...
The thing had one "pin" holding it on, but it was far from being a simple "pin" -- it was a set screw. I managed to Dremel around the thing enough to get it off. It took about 1 hr. Some of that time was spent exploring the rest of the thing to make sure there were no more screws. I knew I had the right side though because the cut-off wheel "sparked" differently.
I basically had to cut a square around the thing and get it wiggling and then twist it out. It was a pain in the ass to say the least, but, now I have my A2 FH on. Gonna be getting either a Phantom or Vortex soon.
Here's a "post-op" pic: