Arrow Spine

Discussion in 'Bowhunting' started by j870sm, Mar 16, 2009.

  1. j870sm

    j870sm Active Member

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    I am wondering if I am shooting to little spine with the arrows I have. I am shooting a 400 spine now. Depending on what chart you look at I can shoot a 400 or a 340. The more I look into this the more I think I should be shooting a 340. I was shooting 65# and again, according to the chart a 400 would work. I have since went to 70# (BH's were hitting low and increasing the poundage brought them in) and it appears that I may need a stiffer spine arrow. I still shoot good groups with what I have but I was thinking that a stiffer spine might stabilize quicker.

    I am shooting 70# at a 29" DL with 100 grain heads. The arrow I am shooting is and Easton Axis ST. I am not sure of the speed as I have not chrono'd the bow since moving up in poundage.
     
  2. dirtball

    dirtball Well-Known Member

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    With the newer drop-a-way rests going to a stiffer spine is usually a good thing. Spine testing arrows when you were shooting around the riser i.e. recurve bow, was very critical because the arrow had to bend its way around the riser as it left the bow. With a two prong rest it is much less critical, and with a drop-a-way IMHO you should shoot the stiffest arrow you can find. When your only option was aluminum that meant a VERY heavy shaft, but with the carbon, or aluminum/carbon ACC you can get to a 300 spine and still be under 10gr per inch of shaft. This has several benefits, first the arrow retains more of the bows energy when it is launched because there is little to no flexing of the shaft, and on the other end you will get more penetration for the same reason. Second, a stiff shaft is much easier to tune, see my other post on Mechanical vs fixed broadheads.
    http://www.longrangehunting.com/forums/f34/broadheads-mech-vs-fixed-40032/index2.html

    Good Luck
    Dave
     

  3. Michael Eichele

    Michael Eichele Well-Known Member

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    What type of cams do you have? What is your draw length? What is your arrow length? What type of fletching? How heavy of a broadhead?

    More info is needed to be able to tell if 400 spine is good or evil. You do not want to weak of a spine as you know, but you dont want to be overly stiff either. A properly spined arrow will offer you much more forgivness than either an over or under spined arrow. Also if youre concerned about quicker stabilization, spine isnt neccesarily the place to start. Fletching is where you want to look. Bigger vanes or a harder angle or even going to real feathers will achieve this better without violating a proper spine.

    Also broadheads hitting low from your field tips isnt cause for more poundage, rather it is a minor tuning flaw.

    Offer some more info and I can help you.
     
  4. RockyMtnMT

    RockyMtnMT Official LRH Sponsor

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    Michael is right. You must have the correct spine. Archers paradox is the bending of the shaft as it leaves the bow. If the spine is too stiff you will have trouble with the arrow planing, especially with a broadhead installed. You want to have at least 10% front of center weight. Meaning: if you balance your arrow on your finger the balance point should be at least 10% of the arrow length to the front of the center point of the shaft length. More front of center like 15% is in my opinion ideal. You need enough weight in the tip to lead the arrow to the target. Not the arrow pushing the tip. Use a 125g broad head and a properly tuned arrow for your bow and draw, and accept the speed that you get. Don't sacrifice proper tune for extra speed. Use the resources that are available from the arrow manufacture. Do you have a good pro shop in your area? This is a whole other subject. There are not very many good ones. Use the arrow manufacture for solid advice on how to set up a properly spined arrow.

    Last word, aluminum is easier.

    Good luck, Steve
     
  5. Michael Eichele

    Michael Eichele Well-Known Member

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    Aluminum arrows are so overlooked these days. The fact is that aluminums are typically starighter than carbon arrows. At least the ones that are economical, the spine on them is MUCH more concistent from not only shaft to shaft but in a 360 degree area around the shaft and from front to back. Aluminum by its nature can be made with much more precision than can carbon. It isnt that carbon cannot be made with precision tolerences like aluminum but it is very difficult AND expensive.

    Thanks Steve for also bringing up the point about weight forward. A decent percentage of weight forward as you stated helps arrow flight espescialy with broadhead AND it also helps the arrow drift less in the wind as well.
     
  6. RockyMtnMT

    RockyMtnMT Official LRH Sponsor

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    I think people forget that it is a primitive weapon. No matter how advanced they get. Things really have not changed in the last 20 yrs that I have been involved in the sport. They changed the shape, picked up 40fps, and made them harder to shoot.

    Back to the original subject. A xx75 Easton arrow will be the most consistent arrow you can get. Learn to judge the yardage and limit yourself to your ability. Speed kills... not necessarily the target.

    Steve
     
  7. j870sm

    j870sm Active Member

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    I have thought about shooting some alum. arrows just to see. With this bow I have only shot carbon. I used to shoot aluminum years ago.

    I tried some 340's the other day and I think I am going to get 6 of them and see.