Busta, went to the hardware store, they didn't have 9/16" x 3/8"x 1/8", I had to get 2 that had the right OD and ID but the thickness was 3/32", putting me at 6/32" thickness, a hair over 1/8".
Free floats the barrel nicely, actually there is a pretty nice gap between the forearm and barrel. If I try on ring I get a bit of contact with the forearm when trying to run a piece of paper between them. I assume the goal is to get clearance, and if I sanded the forearm a bit to get clearance with 1 it should work as well as if I used two ony look better because of the smaller gap?
Won't get a chance to shoot it until next week. I have my fingers crossed.