Thank you. I just got a Heavy Varmint Rest from Brownells, I think something small like 3/16 will work. I’ll break out the calipers and measure.It depends on your rest screws. The first 1s I made were 3/16, when I got a Farley rest I had to make new 1s with a 3/32 hole due to the smaller diameter of the spike on the rest screws. tt