If you are going to test arrows I would like to see how the speed compares with a light or heavy arrow. Most guys will acknowledge a point of diminishing return with weight. It is possible to have a 60# bow that will shoot a heavy arrow the same speed as an 80# bow. It is also possible that your bow could shoot a 800 grain arrow with almost the same speed as a 600 grain arrow. I would be curious to know what your bow does, just for curiosity sake. 
Justin
The difference in speed between 600 grains and 850 grains is almost neglible. It seems that the lighter arrows may only be a few FPS faster, if anything. Oddly enough, I had to elevate my bow about the same for them both at 50 yards. I beleive that with a longbow that bends its full length, until you begin going past the 10 gpp arrow weight, they all shoot about the same speed. Speed didn't die off until I started shooting 900+ grain arrows. I did do a test with a carbon arrow, about 400 grains or so, and found it did shoot more quickly. It also made the bow kick violenttly in hand and left me jerking my bow hand to the left upon recoil
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Seems the old belief that Longbows were better with heavier arrows has quite the ring of truth to it.
