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.
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!