Yea it’s stabilized buckeye burl, I‘ve got a hole jig for grips which makes thins a lot easier. Seems like the hardest part is making the counter sink holes for the screws perfect, we’d to work on getting it set up perfect on my drill press and mark everything down so I can repeat it. But yea I’m set up for doing just about anything.The first set shown looks like stabilized burl? Either way both look almost perfect!
There's really only one way to prevent errors and to guarantee repeatability in regards to hole placement when undertaking manual drilling, and that's to take the time to layout and create a precision hole/drilling template of suitable (read: stable) material that utilizes hardened steel drilling guides. Or you could use 2D/3D modeling software to design both your holding/drilling fixture(s) and the grips themselves, and then create both utilizing a dedicated CNC router and the proper end mills. Perhaps you're already using the latter method to shape the grips since I see a nice tablesaw, moisture gauge, and a healthy supply of lumber also
hoping to eventually, but gotta make sure I get everything down perfect, fit and finish. Got tons of good looking wood I want to use.
For the screw holes you might like to consider using a drill/counterbore combination bit to undertake the process in one step without having to worry about alignment of the counterbore after drilling the clearance hole for the screw; just set your depth once and have at it:
