spine for Heli-m

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This topic contains 5 replies, has 5 contributors, and was last updated by  dshaft55 2 years, 6 months ago.

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  • May 7, 2013 at 10:28 pm #577253 Back to Top REPORT


    Joined: 5/3/2013
    I am shooting a 28/70 helil-m with  400 spine shafts. I can’t get my groups as tight as they should be. Will a 340 spine help tighten those groups? I don’t want to lower the draw weight. Any advice?
    May 8, 2013 at 5:11 am #577259 Back to Top REPORT

    Joined: 10/22/2007
    If you would like to know if those arrows are too weak, then back your poundage back about 3 turns on the limbs and  see how your groups look.  That will tell you much.  You can always buy different arrows if the results improve.

    Mathews S2 / Copper John 4-pin / QAD HD LD / Worlds Best Strings / 808 Bowslings / Easton Bloodlines
    May 8, 2013 at 5:48 am #577262 Back to Top REPORT
    Ohio Timberghost

    Age: 43
    Joined: 1/30/2008
    Location: Ohio
    IMO, the .400’s are very weak for the 70# Helim…FWIW, Im shooting a 28/60 HeliM with GT XT 75/95’s ( .350 spine) and They papertuned and are grouping GREAT. I bareshaft tuned with these and they showed stiff though….Shoot a bare shaft and see if it hits with your fletched arrows….Im guessing it’ll show WEAK ( hitting left of your fletched arrow).
    CHILL 28/70 "BLACKOUT", QAD HDX, Ktech5 twin, HHA XL5519, T3 quiver, Goldtip XT 75/95's, Rage 2 blade Chisel's Drenalin 28/70 WB, B Stinger,HHA DSXL5519,GoldTip 75/95's, Rage 2 blade Chisel's
    May 8, 2013 at 9:06 am #577269 Back to Top REPORT
    Bow Drawn

    Age: 64
    Joined: 11/14/2007
    Location: Ohio
    View My Bows
    Bow Draw weight chart

    This will give you a realistic view of the energy level your setup is and what arrow you should be considering.

    Arrow selection guide

    Carbon Express has made it easy to select the proper spine for your setup.  Several other arrow makers have also made some improved selection adjustments so most shooters can make a better choice in their arrows.

    May 8, 2013 at 9:25 am #577270 Back to Top REPORT

    Age: 72
    Joined: 10/3/2006
    Location: Colorado
    View My Bows
    Generally, a .400 spine shaft is weak out of a 70# bow unless the DL is very short (less than 26″), and even at that a 75-gr point weight is usually required. It is possible to tune for bullet holes with FPs with a weak spined shaft IF form is consistent (no bow hand torque, no string or fletch contact with face/facemask), nocks are precisely indexed to stiff side of spine if there is one, spine consistency within the dozen is very good, etc., but even if tuned for FPs, weak spined shafts will not generally group broadheads well, especially fixed-blade broadheads.

    Carbon Express, Gold Tip, Victory, Alaska Bowhunting, and Easton all recommend a spine between .350 and .320 with 100-gr points for your setup. Check out the manufacturer selection charts for your arrows since recommendation vary depending on weights of components, shaft length, shaft construction (parallel, tapered), etc.

    Carbon Impact and Carbon Tech, recommend a .400 spine shaft for your setup with 100-gr points, but they are the exceptions.

    Check out OnTarget2 free demo software if you want a more precise estimation of the correct spine, especially if you are using illuminated nocks, wraps, insert weights or insert adapters, etc.

    May 8, 2013 at 2:22 pm #577290 Back to Top REPORT


    Joined: 5/3/2013
    Thanks guys, all great information. I cranked the bow down and the groups tightened up…let’s me know what direction to go!{#emotions_dlg.mathews_bullseye_side}
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