I have to say that dealing with GST precision was a pleasure. He made me a 1" Dia brake to fit my 18mmx1 metric thread and bored it to 7mm. The exterior machining was very nice. the chambers had some rough burs, but its not like you can easily get in there to de-burr. I did mod mine a bit, I put a taper from the last chamber down to my barrel outside diameter, as well as put a 11 degree crown on it instead of the flat.I finally got around to installing mine and shooting it today, and there was a very noticeable reduction in recoil. But even better than that was the increase ability to stay on target. Shooting at 100m on 25x zoom, normally the recoil sends me high and to the left off target. With the brake I stayed perfectly inline horizontally and only raised 1 Mil vertically.
Very pleased with the brake
even more pleased with the price.