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Discussion Starter #1
Is there a calculation. Or could someone give me an educated guess. I shoot an elite tempo 70 lbs DW. 32 “ DL. I’m shooting a GT hunter Xt 300. 9.2 gpi. Finished arrow 455grs. Shooting 300 fps. Question??? If I went to an x cutter or something similar at 7.2 gpi. How much speed would I expect to gain???
 

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Try backcountrybowhunting.com and plug in your numbers. These sights tend to be faster than actual chrono speeds.
 

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For a quick calculation, I’ve used that for every +/- 5 grains of arrow weight, you will loose or gain 1 fps.
 

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My Elk Hunting Home
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Every bow is different as to what that average gain or loss will be across a large range of arrow weights. But for my bows 1fps for every 3.5gr of weight seems to work out the closest to reality with chrono speeds. So I'm guessing about a 30" arrow length for you and 2gpi lighter, so 60gr divided by 3.5 equals 17fps........or thereabouts.
 

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generally speaking,...the 1fps for every 5 gr. weight is about right, of course that was established quite a while ago and bow speeds have generally increased since then, so you might see a bigger gain in speed. the other thing to consider, is that today's cams are pretty harsh on the arrows and getting too light ( getting too far outside the "spine box", might give you some pretty wild flight.
 

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Discussion Starter #8
Thanks. I am thinking of shooting IBO. was wondering if it would make enough difference to be worth it.
 
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