So I am considering the HTR for my next bow. Shot it several times and really like it. Here is the question? I ran the specs through shaft selector on OT2 software and I am a little puzzled. 321 IBO, 70 Lbs, 28" draw, 28.5" arrow, 50 grain insert, 100 grain tip, blazers, and no wraps. It says I should use a .400 spine shaft with this setup. Does this not seem weak? Anyone tuned an HTR yet? I would have figured at least .340 or maybe even .300 spine with the 50 grain insert.