I'm no expert either, but say you want a minimum arrow weight of 5 grains per pound for safety sake, so that means 5X58=290. GT 5575's are 8.9 GPI, so the shaft weighs about 253-254 grains. Add about 15 for 3 blazers and 85 for the head and you have an arrow that weighs at least 353 grains, not counting the weight of the nock, insert, or wrap. I think they should be at least safe to shoot and try out. If I'm wrong, someone please chime in!