I grew up shooting aluminum arrows with 1" 3-blade heads from bows that shot sub 200fps. Unless I hit hard bone I always got pass through hits. Then carbon fiber arrows came out, bows began using cams & strings instead of wheels & metal cables, and for awhile it was all about speed. Still regularly got pass through hits. In recent years I had been using sub 400gr arrows with the biggest mechanical heads I could get, and from a 70lb x 30.5"dl bow I generally always got pass through hits. A few years ago this heavy arrow cut on contact broad head stuff began buzzing so I switched to 530gr arrows just to see what the buzz was all about.
My new arrows were 240 spine so stiff as rebar, 530gr with heavy brass inserts, but I kept using the same giant mechanical heads and bow. Of the six bucks I killed with those arrows I never once got an exit wound. Not a single pass through. First time was 20yds away double lung through ribs only and the arrow didn't puncture through the opposite side. I was perplexed but curious so I shot 5 more with same results. I feel that was a sufficient sample, an honest effort. Now I'm back to 400gr 350 spine arrows and not looking back. That's all the proof I need.
If I had used a cut on contact fixed blade head then I probably would have gotten pass through hits. But I use a huge cut expandable that I trust and don't want to change. Nothing was wrong beforehand, no penetration issues. I was just curious so I tried the heavy arrow, and found that with same head and same bow it did not penetrate as well as a faster, lighter arrow.
