I have a couple of 4 by 7/8 and a couple of 5 by 3/4 c and h research stock models if the digging above is fruitless.
The reducer is for a SCTP shooter who has a new Browning Citori OU. It is very barrel heavy and seems to recoil into his face which could be a pitch problem. He said the bolt hole is 0.93 (15/16) and 6.5 inches deep. I am thinking at least an 8 oz. reducer to make it a little more balanced and relieve some of the recoil.
DAS, I have one pulled from a stock I sold. You’ll need yo add some wrapping to it to fit snug in the hole (was hell to get out) but will definitely work. It’s right at 10oz. PM me your/his/her shipping info and I’ll get out so the young man/woman doesn’t get beat up. Good shooting, Rey