I drill for wedges when the stock is still squared up, but barrel is inletted with the
loops installed. I place the barrel in position on top of the stock at 90 degrees so the loops rest at the correct points, and using a square, mark across the top of the stock where the tenons ( or pins) will tho crosswise in the stock from side to side . Then take a square ( remember to have the top of the stock…square…..straight……and level). Then transfer those lines from the top down the sides of the stock to show where the slots for the wedges will be located.
Now place a “fence” …..could be angle iron or a board……to butt up against the top flat of the barrel on the drill press table and clamp it in place so that the drill when lowered in the drill press will just clear the bottom of the slot in each staple ( for straight barrel…..swamped barrels require resetting for each slot) you may now set the barrel up , clamp in place, and drill your series of holes for each loop (on a straight barrel…..swamp requires slight reset for each one due to different dimension foe each slot. ) This has worked well for me several times. Sound complicated,but is very simple and easy.
An addendum: It’s easy to adjust the force the wedge applies vertically by putting a slight bend in it to apply more pressure to the bottom of the loop.
( but you all knew that !………I had to find it out….after enlarging my vocabulary)