eeerrrr...I can't speak for your bow, but it won't ruin mine, Just kidding, actually I shoot close to 6 grains per pound, 413 gr. for the most part, and haven't ever bothered to chrono them, but I was averaging almost 300 fps (sometimes over actually) with an arrow that was about 5.2 grains per pound with my lil' 29" draw. But I feed my bow a steady diet of heavier arrows lately, since I switched to ACC's. I think you will reduce your long term bow life feeding it a steady diet of light arrows, but I think the differences aren't as pronounced as some would like you to believe (otherwise most of the big manufacturers would not waranty their bows for 5 gr. per pound arrows).

Gordon