I have been experimenting with heating the metal part to about the temperature that straw color first appears. 350-400*F? I then press the part into the tight inlet and let it cool. It does not burn the wood. It does seem to soften the lignen and make a perfect fit. IF it smokes it is too hot. Somebody here gave me the idea, it works. I am not sure if I'd try it on a whole barrel, , maybe a better gunsmith than I can comment on the idea.