I've had this break since 1991 or 1992. I bought it at Knob Creek. I was told it was made of 6 pieces of SS that were welded together. I remember it cost a lot but I can't remember how much. I bought it after seeing a 100lb girl dump a 30 round mag without the gun moving.
The markings are: "AR15", "BDM", "PGRS1" and "32893".
The holes shown on the brake are duplicated on the other side. There's also another (3/8"?) hole on what would be the top of the brake when indexed correctly on the muzzle.
I've only shot it a few times but I do remember it is without a doubt the most effective brake I've ever used.
Below is a pic- your help is much appreciated.