You have to be careful with pignut. Seriously, only use what's under the bark. Nothing else. If it's outside the bark, it's useless for bowmaking.
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I've had the pleasure of making a few bows from pignut hickory. In fact, the very second bow I ever made was pignut. Took me over 40 hours to get the bark off because the first growthring had some crazy undulations! Debarked the whole thing using a pocket knife to scrape. I love that bow. That was about 8 years ago and the leggy redhead that I gave it to still shoots it. nIt's taken no set, no splinters lifting, looks as good as the day I gave it to her. But then we have almost no humidity here and there's 69" of bow for a 27" draw - overbuilt!