Just used my new AR tools to disassemble a 20" Armalite with ban type pinned and welded muzzle brake. I was confused by the fact that there was only one spot weld visible. Someone here told me the pin was on the side and installed like a FSB pin. As I found out, that is basicly correct except the pin is in a blind hole.
I took the barrel off the rifle, knocked out the FSB pins, only to realize I couldn't slide it off the barrel with the brake in place. Put one pin partially back in and chucked the barrel extension in the lathe chuck. Supported the muzzle end with a live center and proceeded to machine away at the rear portion of the brake. After turning the brake down a ways, I was able to see both end of the pin. I kept machining the brake until I was sure I had all of the weld material gone, about .600" dia.. The pin came right out, but the brake would not come off. Didn't want to get brutal, so I continued turning the brake down. When I got to about .530". dia., the back end of the brake separated and I could see the barrel threads. The brake came free and I was able to unscrew it from the barrel. The threads look fine.
I took pics of the process. Email if you are working on one of these and need some help.