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Discuss Tuning / spine etc at the Methodology, Tuning, Coaching etc. within Archery Interchange Forums; Is there any obvious reason why my arrows are too stiff? I tried following the ...
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    Tuning / spine etc

    Is there any obvious reason why my arrows are too stiff?

    I tried following the Easton guide - did I get any of the settings wrong? Also do I go one step weaker or more?

    My AMO Draw length is 30 7/8"

    The poundage of the bow is currently measured at 34.3lbs

    The way I read the arrow chart put me as a T7, with the poundage making it very close to a T8.

    For ACC arrows the T7 box gives these two options:
    3-18 560
    3-28 500

    For ACC arrows the T8 box gives these two options:
    3-39 440
    3-28 500

    So I figured the 500 spine were a safe option.

    However I tried a bareshaft tune.

    I installed a matchstick to make the pressure button solid. I set the centre shot (as best as I could - using tape on the limbs with marks for alignment) and I set the rest height. I shot fletched arrows and set the sight until they were going into the gold (20 yards - 60cm target). Shooting the bareshaft goes to the left missing the 60cm target altogether (but hitting the boss).

    I have 85gn and 100gn points. The 100gn points are a bit better but it isn't enough of a difference.

    My limb bolts were nearly all the way in, I only had 3/4 of a turn left. I have tried winding that in (But haven't shot again yet) - however the poundage only went from 34.2 to 34.3lbs - so I don't think it will make a big difference.

    Is it worth trying a bit more weight to weaken the arrow, or is my FOC going to go too far out?

    I forgot to say my bow is on the maximum recommended bracing height.

    Hoyt Horizon 25" Riser. SF Elite Fiber Foam limbs - Long rated at 28lbs @ 28".

    Anything else to try?





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    Okay, so arrows about 30 inches and weight 34lbs... I see that as a T6 on the charts. If your shafts are over length, then it's more difficult to judge (an AMO draw length of 30 7/8 would mean a shaft length - as used by the charts - of 30 1/8).
    You could get up to the lower end of T7 by increasing the weight over 36lb. Or by increasing draw length and shooting a longer shaft, but that's not so easy. A 500 spine basically looks too stiff, by a couple of grades. You can't compensate for that with point weights.
    The simplest way to get a match would be to increase the draw weight, but you'd probably have to go up as much as 5 pounds.
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    I've got a set of 3-18, and the AMO length is 30". I've had trouble tuning them, and only got a tune by increasing the draw weight to 39lbs. They now shoot very slightly weak. I also tried 100gn points at 36lbs as that was the weight I was wanting to draw, but couldn't get a tune.

    I had to do paper tuning to tune the centre shot, so it might be worth checking that. I ended up having to move it quite a lot further to the right from I initially set it.

    Sent from my LG-H815 using Tapatalk

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    Shaft length if the acc arrows is 30.25" the point is level with the clicker extension bolt so it sits in from the edge of the riser.

    I think I used amo rather than shaft length when looking at the chart. So that would explain it a little.

    My only way to go up poundage wise would be to change the limbs.

    I'm not sure that I'm ready for another poundage change yet.

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    Quote Originally Posted by nbuuifx View Post
    Shaft length if the acc arrows is 30.25" the point is level with the clicker extension bolt so it sits in from the edge of the riser.

    I think I used amo rather than shaft length when looking at the chart. So that would explain it a little.

    My only way to go up poundage wise would be to change the limbs.

    I'm not sure that I'm ready for another poundage change yet.
    The charts assume a shaft length of 1 inch past the rest. Assuming that's about at the pressure point (which is a slightly dodgy assumption), it's AMO draw length minus 0.75 inches.
    But the chart steps are an inch at a time. So "30" on the chart covers 29.5 to 30.5.
    30.25 would be well into the "30" section. 34lbs is well under the border, so 34/30 is a good starting point. They're both in the upper part of the range, so it's possible that a weaker T7 might be made to work.

    There are minor tweaks you could try - raising the bracing height, adding a lot of point weight (100 grains won't do it: 200 might give some movement). But I wouldn't hold out much hope of getting 500s to match.
    On the plus side, stiff shafts might not behave too terribly even if they don't strictly work. Might not group as well as well matched shafts, though.
    Ever tried? Ever failed?
    Try again. Fail again. Fail better! - Beckett

    The marksman who hesitates is lost. Just take it for granted that you are going to hit and fire away before you have time to doubt the certainty of success. - Annie Oakley, 1894.

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    Thanks, I might try filling the points with solder to see what happens. Will that have any negative effect on FOC or distance they can travel etc.?

    Bracing height is already max recommended.

    The fletched are grouping OK at 20 yards - they were mostly going in the gold on a 60cm target. Only one or two went out of the gold and I would put that down to me rather than the arrows. That was shooting with the matchstick in the button too.

    Luckily these were second hand so I haven't spent a huge amount out on these. I might just put them to one side and try and find another set if adding more weight doesn't help!

    If it makes any difference, with 85gn points installed they miss the boss. With 100gn they miss a 60cm target (positioned in the center) but hit the boss. So the small increase of 15gn seemed to make a difference.

    So what do you think the best spine to look out for in another set would be?

    Thanks

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