I have repaired several - hasn't been mentioned, but you will want to drill pilot holes! Trying to drive a wood screw type butt plate screw into end grain of a birch/maple/oak plug will either strip or split - gun repair articles often mention using the actual screw coated with soap to "thread" the pilot hole as well, before actually installing the butt plate - can be a real challenge to exactly re-position those screw holes to get the original butt plate back into its exact original position and not overhanging one side and "underhanging" the other side!! Not real certain where the "little bit bigger than OD" came from? I can see wanting the dowel plug to be longer than the screw. Slip fit between dowel and parent stock - higher end wood glue - perhaps a slice or two along the round length of the dowel to allow excess glue to "vent" out of the hole, and the glued-in dowel will be virtually as strong as the original wood was. Too tight of fit in hole will "glue starve" the dowel along its length. You might want to be fussy enough to shape the bottom end of the plug to match the shape of the bit that you drilled the hole with?
These are all good points.
- your plug should be longer than the screw
- either put a couple of grooves in the plug or I use a triangular file and file a helical groove. (only take a couple minutes) - you can also sand the plug a bit so there is some clearance - as mentioned, don't starve the joint.
- drill your plug holes using a brad point bit if you have one (best option in end grain & leaves a (relatively) flat bottom) twist bits tend to wander in end grain.
- let it set/cure, file off the plugs flush with the butt - you probably won't have to wait long, you will be drilling into the plug, not the joint - so 1/2 hour is just fine.
- fit your plug and use center finding punches to locate your pilot holes. Your pilot holes should be as close to the same diameter as the web of the screw. If it has a shank the same or larger than the threads, you will need to come back with a larger bit same size as the shank and drill that only deep enough to allow the shank to clear.
- you do need pilot holes as Potashminer mentioned.
- drill them absolutely perpendicular to the plane of the butt plate, a couple degrees backwards, forwards or to either side and your screw won't sit flush in the plate as Potashminer noted. (and that really looks like hell)
- I like to use beeswax on all my metal to wood fastenings like this. but soap will work too.
- start
screwing.
The fun thing about this kind of hidden repair is that if your screws are not sitting nice and flush with the butt plate, just drill out the plug and try again.
I don't know where "a little bigger than OD" came from either - you want enough material there to hold the threads ... the bigger the plug you use, the wider your margin of error when drilling pilot holes
