A Pipe and Underlug Pin Drill Jig

[Herb]

Here is how I drill holes in a shaped stock for pins.  I made the jig from a piece of angle iron, filed square inside so I could measure exactly from the top. You can
make this from wood for single use, and I think aluminum angle would be great.  Say you have a 1" barrel and .095 pins.  Measure the barrel thickness and HALF the pin thickness and centerpunch that dimension inside one leg of the angle.  Drill the hole with your drill, I'd use a No. 41 drill here.  If you use a key, drill a hole on either side so you have three in a row.  I also drill a "peep" alignment hole above.  To use, with the barrel in the stock and the center of the underlug or rod pipe marked on the side of the stock, position the stock in your drill vise so it is level and square, the centerline under your drill bit.  Adjust the stock so the drill will enter the center hole.  With the barrel squeezed into the stock with the vise, turn the drill on.  Adjust the vise by tapping with a mallet so the bit centers on the hole.  Drill the hole clear through.  If you need a wide hole for a key, adjust the stock laterally and drill the other two holes.

Drilled hole- the bit was larger than the slot.

Drilling a pipe

[Herb]

For swamped barrels, find the nearest hole that will work (if you made multiple guide holes as in my example).  You can shim the top of the barrel with cardstock to adjust a hole exactly.  Or you can drill a single hole at the exact location.  For pins, I like finishing nails or sheetrock nails, which are .095 with no burrs on the point.  Coat hanger wire also works well.  Anything bigger than about .070 works OK, but 1/16" bits will deflect if you hit the pipe barrel or the rifle barrel.  This jig achieves exact placement of the holes, even in shaped and rounded stocks.  If you want to drill a centering hole, the sheet rock nail with the head cut off will do that.  It is not necessary.  Just drill your guide hole the same size as the drill bit you use.

[Herb]

To locate the hole for a rod pipe, I put the pipe  in place, squeezed down, and measure from the top of the barrel to the bottom on the pipe, or entry pipe in the bottom photo.  Then I subtract the distance from the outside of the pipe to the center of the tab and drill the hole that distance from the top of the barrel.

[PPatch]

Thank you Herb! I will be doing this soon and have some old angle iron about - looks like a fairly fool proof system (Just what I need... hehehe)

Cheers

Dave