Saw the head off a 2" finishing nail. I filed a notch on the inside of the fixed jaw of my Versa Vise near the top right edge, .2" long. Place the sawed end in this notch and tighten the vise. (I also filed a notch around the jaw and on the back side). Hammer the nail around the vise jaw and the back side. Mark it for length and snip or saw it off. Tap the legs parallel if needed. Then I place it in a jig made from a piece of 1/4" steel, with the .1 inch holes drilled on half inch centers. Drive the staple into this (grooved between holes) and file off any protrusion. Tap it out. Staple now has legs 1/2" on centers (same as Track's center punching tool). The legs are .2 long. I slightly champfer the ends and cut a little shelf like Fergetful Jones does. Locate where I want them on the bottom flat of the barrel (very important!). They can be placed to the edge of the flat if they would otherwise come through the ramrod groove.
Center punch for the holes. I set the barrel in a vise in the drill press, bottom flat up, level both ways. Put in the .1 drill in the chuck and make sure it runs true. (Mike the nails, they vary in size. Use a No. 39, .0995, file the nail to this size if needed, or if the nails are smaller, use a smaller drill.) Adjust the table so the quill in full down position just lets the drill touch the centerpunch hole. Then loosen the vise and place a .1 inch thick shim under the barrel, which raises it the .1 inch the drill is to cut into the barrel. Drill that hole and reposition for the second one. Repeat for the other (two) staples, keeping the barrel level both ways. Tap the staples in lightly, with a piece of .1 nail (which will be your stock pin) inside the loop, as a gauge to be sure the staple is down in the holes. Stake around them with a center punch to crowd steel over the foot of each. I file the top of the staple off (which is the bottom when in the stock) to thin it so it is less likely to come through the ramrod channel. You can also file inside to loosen it if needed. If you have a 3/4 or 13/16 inch barrel, you might not want to drill that deep a hole, but being on the edge of the flat leaves more barrel steel below the hole.