Fiberglass arrows won't shatter out of a compound. At 70# you'll be getting a lot of flex though. I'd suggest dropping the weight down as much as the bow will let you. Check out the Muzzy Carbon Mag arrows too. They are solid carbon arrows and are stiffer than regular shaft.

There are also combination carbon/fiberglass arrows made by Cajun Archery that are stiffer than regular fiberglass arrows.

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