True IBO test standards are for a 350gr arrow fired from a bow with 70lb peak weight and a 30" draw. If the bow model is not capable of satisfying these standards (i.e. a youth/ladies bow) then they are tested at their max draw length (if less then 30") at peak weight with an arrow that weighs 5gr/lb peak draw weight.

As far as "busting up" limbs, you'll need to provide some evidence or at least site your source. I highly doubt that manufacturers would endorse the use of 5gr/lb arrows under warranty, or allow IBO to set a 5gr/lb standard for testing if their bows couldn't handle repeated firing as such.

Mike