So I have always shot Ironwill Broadheads and they always fly like darts. I bought a new bow this year and I can't figure out why my broadheads are flying so poorly. First my set up is as follows: A Mathews V3 31 with a 28.5" draw at 70 lbs. Shooting Easton 5mm FMJ's 340 spine that are 27" and 3 fletched with blazer vanes and a wrap underneath. I have a Ironwill 100S up front. Total arrow weight is about 462gr. My field tips and my mechanical broadheads fly perfectly all the way out to 80 yards and hit the target right where I am aiming. When I shot my ironwill's today the first shot was at 20 yards....I missed about 18 inches right and into my fence. The second shot was at 8 yards and I hit about 4 inches left of the center. The third and final shot was at 20 yards and now missed 12 inches left into my fence. When shooting at 20yards I could almost see my arrow dancing or knuckling in the air. I basically watched it take a hard right or left off target. I switched back to field tips and NAP mechanicals and they flew perfectly at 20 yards and 40 yards. My guess is that I am underspined at 340? I ordered some 300 spine arrows that I am going to 4 fletch rather than 3 fletch hoping that solves the problem? Any other suggestions? Thanks guys!