Can someone explain arrow specs to me (grains, spine, etc.)

Discussion in 'General Archery Forum' started by krist003, Feb 28, 2008.

  1. krist003

    krist003 New Member

    I am trying to pick an arrow for my bow. I shoot a 2007 Diamond Black Ice 61lb. draw weight, 27" draw length, 26" arrow. I want to mostly hunt deer and elk with it, as well as target shoot in the backyard.

    I am confused with all the different manufacturers ratings. I will be shooting Easton arrows, so lets stick with their system of measurements.

    Does a 340 arrow deflect less than a 400 arrow? What does the 340 and 400 mean? That is not grains is it? What about grains per inch (GPI). When someone says they are shooting a 350 grain arrow, how is that measured? Is it the GPI times the length or something? Or the overall weight with nock and insert?

    As you can see, i am confused, and my head hurts. Someone please straighten me out. Any help is always appreciated.
  2. QSA

    QSA One eyed/Gutless wonder


    Lets is if I can help.
    340 and 400 is the amount the arrow flexes when a set amount of weight is hung on it. So the 340 is stiffer.
    GPI is just what is says Grains per inch, that is how much an arrow weights per inch. You should no go below 5 grains per pound of draw weight, So at 61 you want no less the 305 grain total arrow weight.
    Over all weight of total arrow put together. Broad head an all.
    When putting your arrows together. Use the same weight target points as you are going to use broad head weight.
    When building arrows always try to keep all of them the same weight with in a few grains. But you will find to get the arrow weight lite enough to shoot max speed will be pricey. Shooting a heavier arrow is fine, but get the right spine that matches your draw weight first and go from there.

  3. Holy Smokes

    Holy Smokes Senior Member

    Here is some charts that may be helpful to you
    any questuions on reading it pls ask Smokes
  4. krist003

    krist003 New Member

    Thanks, guys. I totally understand now. You multiply the GPI by the length arrow you are shooting and add the weight of all the stuff on it (tip, insert, nock, vanes) and you get your final weight in grains.

    I appreciate the help. One more question, how do i know what deflection i need - 340, 400, etc. (In Easton sizes)?
  5. HCAman

    HCAman New Member

    According to TAP, an Archery program I have, you need a .400 spined arrow with 100 grn tip with insert.