Yes, the screw hole is countersunk / recessed for the head of the screw, and the rest of the hole is a smaller diameter for the screw shaft only. If the screw hole is added, it will cost a little more and I can only guarantee that it is a perfect match to the donor Sidkit grips I am borrowing. If they do not fit everyone's Sidkits, I am not in a position to offer refunds so caveat emptor.
Can someone post (or send me) a clear pic of the hardware used to attach the grip, preferably with a good measurement of the screw head. In order to do a predrilled, countersunk hole I need to do it precisely so the screwhead neither sinks too low nor portrudes beyond the surface of the grip. It will take two passes for each grip, one for the shaft diameter hole, another for the screwhead countersinking. Another issue is the screwhead itself, is it a flush (square) cut bottom or does it taper down to the screw shaft diameter?
One possible compromise for a value engineered solution, perhaps I can do the countersinking for the screwhead (depending on the bottom shape) and let the buyers finish it off. That means only one pass per grip, which also means less cost to pass on. Whatever the consensus is, these grips are for you guys. I should have my first walnut prototypes out this weekend if things work out right.
It isn't a hard do it yourself job. You take the mirror image Sidkit grip and match it with your walnut grip, mark the hole and drill it. Then reverse it and drill a slightly larger hole or dimple the hole to accomodate the screw head. If this is a typical replica, a firearms grade high quality screw may not have been used so this is a chance for you to dress up your gun a little. Go to the hardware store and buy a matching size but better quality screw. I don't know what Siderio provided with his kits, so I am not saying that you need to upgrade the screw. Anyway, just my thoughts on saving some time and (buyers') money on this project.