I used a Magpul Type 3 QD socket which includes a 10-24 1" screw. When you open the buttpad and look inside you can see the two moulded "pockets" for the QD sockets on each side. I think it is designed for a Magpul Type 2 QD socket as it is a little shorter, but then you do not get a machine screw with the Type 2 kit. The perfect match would be a Type 2 socket and a 1" machine screw.
I opened up the pocket with a 15/32 drill bit in a hand held chuck. I think an electric drill would go too deep too fast. I then opened up the hole a little more with a 1/2 inch bit, again turning it slowly by hand to the depth I wanted. Finally I smoothed out the inside of the hole with a 1/2 tapered reamer, again by hand.
At that point the QD socket is a tight friction fit, but it has some serrations around the lower outside of the QD socket that need to be taken down to the diameter of the rest of the socket and hole in the stock, I did that with a couple of swipes on the grinder. I finally made a slight bevel with a file on the outside bottom circumference of the socket so it would ease into the hole. I then used a plastic faced mallet to tap the socket into the hole. The screw went in from the other side. Because I used the longer Type 3 socket the material was really thin on the inside of the moulded stock socket hole once I had drilled it out, so I reinforced it on the inside of the stock with some JB Weld.....the socket isn't going anywhere. This would not be an issue if you used the shorter Type 2 socket and thus you would not have to drill as deep, if that makes sense.
I would advise against using power tools, unless you are very skilled, which I am not!
