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Thread: Can someone put arrow selection into plain English for a rookie??

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  1. #1
    sniperjohn
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    Default Can someone put arrow selection into plain English for a rookie??

    Good morning & thanks for any advice. First post as I'm a new Martin owner. After shooting 11 bows for fit & feel, I got a Cheetah a couple weeks ago.

    I bought some Easton Carbon Arrows at Dick's, 9.5 GPI, and put on 100 Gr. field tips, then went to a friends house who owned a chrono. We found that I shot a full 30 FPS faster with his "Flatline 500's" that weigh 6.5 GPI. That sparked several days of confusing research that I'm hoping someone can simplify a bit for me.

    In order to get a few more FPS without blowing an arrow apart/through my hand, how light an arrow can I safely shoot at 29" draw, 70#, 100 gr. tips, arrows cut to 27"?
    And what's the critical measurement..."Grains per inch" or the "200/340/400/500" info found on the charts on the arrow boxes?

    Thanks so much for any help!!!

  2. #2
    Senior Member alex's Avatar
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    My english will be plainer then you expect (see where i'm from ), but here: the rule is that you must shoot arrows which aren't lighter then 5 grains per pound - so for a 70# bow the arrows must be at least 350grains. Arrow spine is something different - the different arrow companies has different markings for their arrows, but as far as i know a good spine for a 70# bow is about 350. May be the more experienced guys here will correct me if i'm wrong.
    2008 Martin MOAB - 45-60#, set at about 51-53# / 55#" Perfect Line" compound/ 55# Mongol horsebow/ 45# "Perfect Line" takedown recurve/ 45# Bearpaw Grizzly hunter recurve/ 55# Samick Longbow Cheetah ... and several homemade bows

  3. #3
    sniperjohn
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    Thanks, Alex. I understand your math & it makes sense.

    9.5 GPI X 26.25 " = 249 grains...then add a 100 grain tip, and you've got a 350 grain arrow.

    So, when I look at archery forums, how come so few are shooting arrows that adhere to that math? Seems a great number that should be shooting 350 grain arrows are shooting between 270 and 300. My research tells me that's unsafe and could result in blowing up a shaft and possible injury or causing damage to your bow...

    Is that correct?

  4. #4
    Senior Member alex's Avatar
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    Quote Originally Posted by sniperjohn View Post
    Thanks, Alex. I understand your math & it makes sense.

    9.5 GPI X 26.25 " = 249 grains...then add a 100 grain tip, and you've got a 350 grain arrow.

    So, when I look at archery forums, how come so few are shooting arrows that adhere to that math? Seems a great number that should be shooting 350 grain arrows are shooting between 270 and 300. My research tells me that's unsafe and could result in blowing up a shaft and possible injury or causing damage to your bow...

    Is that correct?
    That's why i'm only in this archery forum May be they mean only the bare shaft to be 270-300, when you add the nock, fletchings,insert and tip you have a proper arrow weight... For hunting you definetely need havier arrows. You're correct that the effect of a light arrow would be like of a dry shot.And your warranty will be gone if you use a lighter then 5gr. per pound arrow too.
    2008 Martin MOAB - 45-60#, set at about 51-53# / 55#" Perfect Line" compound/ 55# Mongol horsebow/ 45# "Perfect Line" takedown recurve/ 45# Bearpaw Grizzly hunter recurve/ 55# Samick Longbow Cheetah ... and several homemade bows

  5. #5
    Administrator bfisher's Avatar
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    John,

    Welcome to the tech forums and good luck with your bow.

    Don't let a couple of these guys snow ball you. Alex is from Bulgaria and Simon (Montalaar) is from Germany. Lord knows who else is on here. Anyway, their English is pretty darn good. Many Americans should take notice and not be so lazy with their grammar or typing. Occasionally misspelling something is quite different.

    Now exapnding on the arrow business, assume we're talking about that 9.5 GPI arrow with tip you mentioned being 350 grains. To this you also have to add the 15 grain insert and 12 grain nock. Then add about 16 grains for Blazer vanes or 30 grains for standard 4" vanes and you'll end up with an arrow that weighs 375 to 400 grains.

    As Alex mentioned weight is not the only issue. Getting the correct spine is more important and for your specs it's pretty hard to spine properly and shoot an arrow too light in mass weight unless you go some of the ultralite shafts.

    I have a question though. With a 29" draw how in the world can you shoot a 26.25" arrow? It doesn't matter a whole lot, but if you see yourself getting too light with the arrow it's easy to just leave your arrows a little longer which might force you to shoot a stiffer spine. In most cases the stiffer arrow is going to carry more mass weight, too.

    When you look at all the different arrow on the market pay particular attention to the SPINE rating. Don't always go by the number printed on the arrow. Several companies list them differently. That's where the arrow selection charts can be used. Easton/Beman are arrows that have the true spine on the arrows and do the Ultralite series from Gold Tip.

    For instance, a Carbon Express Maxima 250 is not a 250 spine. It's closer to 400. A PSE 200 is not a 200 spine. It's closer to a 400 spine. See what I'm saying? You have to cross reference the number to the spine charts. Nice and confusing isn't it?

    For your setup, 29" and 70#, medium cam, and 26.25" arrow I would almost think you could shoot a 400 spine. Somebody with some computer software might help out on this. If the 400 shows a little weak then you could almost certainly choose a 340 spine. Si find the arrow spine you need and then start looking at arrows in that spine that weigh enough. Don't forget to add all the other components.
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  6. #6
    sniperjohn
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    Bfish, thanks for the input. As for the draw Vs. the arrow length, my friend (the lifelong bowhunter and arrow-speed-junkie) suggested an overdraw in order to get my arrow weight down. I'm not convinced it was the best purchase I've made, and may go to slightly longer arrows and get rid of it soon. Don't know...

    I haven't been taking the other components into consideration, but will going forward.

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