I'll try to make this short and sweet. I really don't know why your arrows are breaking. I've shot all kinds of arrows over the years from aluminum, ACC's, and lots of different carbons and can say with relative certainty that none are impervious to being damaged. Regardless of what others may say none are indestructible.

As a matter of routine I'm a speed freak so buy thin walled, light arrows. I shoot upwards of 15,000 shots a year. Although I change around a lot I have arrows that are ten years old or older. Mostlythere are still 9 or 10 left of the original dozens. One thing I have learned is not to group shoot any more. After a while it just doesn't make any sense to bust my own arrows to prove to myself that I can. I know I can.

In your case, like I said, I don't know what the problem is, but I seriously doubt that it is just the arrows.