I don't know what an octogon barrel is, mine is round, just like the 14 in I sold, {wish I hadn't},doesn't taper or anything. Deer season opens the 16th, so I don't have time to look for a bull barrel, don't know if it would work for me, anyway..I put on the long foreend, maybe that will help some. I really appreciate all of you trying to help, you're a great bunch.