That tool is awesome! But l’d probably goof up and still get an off center crooked hole.
If ii want a sling, which i generally dont, Here is what I do.
Figure out where you u want the holes,by comparing to other similar stocks with stds/ swivels. Think about any issues you’ve had with them. Like , do they interfere with using a front rest, or a rear bag. Or resting on a branch or ledge,or shootinng sticks. Do You want to use a bipod . And use tape to Mark the spots you want. Too fclose to the ends is bad, cause the wood is weakest there. 2 or 3 inches in is probably ok.
See if the sling you want to use , works at those marks. Is it long enough, is it to long. Will it work ? That also depends on what you intend to do with the sling. If its justa carry strap and adjustable , you’re probably good to go, but if you intend to uss it as a shooting aide, to secure the rifle to your off side , by slither or tourniquet methods you need to make sure your off hand will be where you want it..
Wait a day or two and think about it all.
Take the stock off.this a good time to clean up the inletting and seal the wood on the inside.
Secure the stock on your workbench. Between your knees. Is not. secure.
Pick a wood drlll bit slightly smaller than the stud screw , chuck it up shorter than tthe stud screw. I.use a small dremel type tool cause a drilll is to big hard to handle and harder to see what im doing.
Touch the drill bit too the wood. Back off and see that the pointy mark is where you want it. Put it back in the same spot , make sure you are square and that the hole will be straight relative to the stock, so te stud will fit flush. Drill slow.It will be fast you aren’t going far.. be exttra careful On the for end, you don’t want tto go through or create a bump in the barrel channel.
Clean out holes , seal the wood, gun wax is fine,,and it helps the screw bite into the wood best. Put spacer ring on stud , stud in hole,make sure it’s straight and start turning in by hand, onece its going in straight,i use an allen wrench thru the stud hole to gain leverage, if its too tight, stop, use a rat tail. File to enlarge hole a little.