I made my own similarly, except I used brass threaded inserts in the stock, for the clamping screws. They have a coarse thread outside for screwing into the wood, and 1/4-20 threads inside. Knobs with 1/4-20 thread are used to adjust, with the ends ground to a point. The vertical studs were notched with a Dremel, to give 1/4" adjustments. I picked a comfortable spot before notching, with black magic marker on the studs, tightened the clamp screws to leave a mark, then used the marks as the zero notch place, with +- 1/4" notches from that spot. The threaded inserts are used for takedown furniture assembly, normally. I suppose it would be possible to split the buttstock, if you tightened the clamp screws excessively, but the stock was a Savage laminated--strong, like bool!
