I made a couple powderhorns and horn containers with only a friction fit plug, but had one plug shift and another in a horn container come loose completely, so I peg all mine now. I use toothpicks, breaking off the end but leaving just a little bit of the factory taper, put a dab of glue on the end and drive them into a drilled hole. I find 5/64" works better than 1/16", as they fit tightly without breaking. If you have a jeweler's saw with a fine blade you can use that to cut the remainder off, then trim with a sharp knife or chisel.