You aren't much over 400 grains. You are pulling 55-56@29. Those arrows are a bit on the light side--I'd stay with at least 8 grains per lb (you are close).

I shoot 66@28 on my Crusader longbow and I don't break many cedar arrows, but I usually hit the target. If you stump shoot/rabbit hunt/etc. where you are likely to hit trees/rocks/etc., you will probably break several--'course those are hard on any arrow. I usually make my own (I buy the shafting) or a friend makes them for me, which saves me a lot over buying finished arrows.

Heavier arrows are (to a point) better for hunting--they are quieter, easier on the bow,less apt to get deflected by a twig or wind, and penetrate better on large animals/heavy bones. 10-12 grains per lb seems to be optimum for most bows. You can add some aquarium tubing, weedeater line, and probably a few other thingsinside your carbons and get the weight up some.

Chad