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Thread: Arrow question?

  1. #1
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    Arrow question?

    I recently got some new arrows from the archery shop. I usually just let them take care of things since I'm no genius when it comes to archery tackle. I've been shooting/ hunting archery for around 10 years now. Some years I don't even archery hunt, it really all depends on the tags I draw. I also hunt with rifle and muzzleloader. Haven't archery hunted for a couple years now. So here's my question...

    I've got a 27" draw, shooting 400 spine arrows with a 100 gr tip. I was thinking about going with a 125 gr broad head to increase the over all weight of my arrow knowing it's on the lighter side. I looked at a chart on-line and it looked like I would possibly be under spined if I moved up in broad head weight? Or at least right on the bubble.

    Got me thinking... I hear "under spined" all the time but not really "over spined". Is there such a thing? If so what are the down falls to being over spined? I was thinking I could go to a 340 spine which would work better with the 125 broad head? Although, 400 spine seems to be recommended for my draw length. Thoughts???

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    Quote Originally Posted by CoHiCntry View Post
    I recently got some new arrows from the archery shop. I usually just let them take care of things since I'm no genius when it comes to archery tackle. I've been shooting/ hunting archery for around 10 years now. Some years I don't even archery hunt, it really all depends on the tags I draw. I also hunt with rifle and muzzleloader. Haven't archery hunted for a couple years now. So here's my question...

    I've got a 27" draw, shooting 400 spine arrows with a 100 gr tip. I was thinking about going with a 125 gr broad head to increase the over all weight of my arrow knowing it's on the lighter side. I looked at a chart on-line and it looked like I would possibly be under spined if I moved up in broad head weight? Or at least right on the bubble.

    Got me thinking... I hear "under spined" all the time but not really "over spined". Is there such a thing? If so what are the down falls to being over spined? I was thinking I could go to a 340 spine which would work better with the 125 broad head? Although, 400 spine seems to be recommended for my draw length. Thoughts???
    If you are on the line, you should for sure bump up in spine. In my experience, you are better off to go a little over spine than be under spined. To answer your question about being over spined, Im sure you can, but I never have been.

    A stiffer arrow will tune better than an under spined arrow out of most compound bows.

    I bet a 340 shaft with your setup would shoot good. You could even put in a heavier insert and keep your 100gr heads if you want.

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    Cool

    I shoot 340 with 125gr. heads works great except in wind.Never tried anything stiffer or heavier.Just hunt stink pigs and Muleys.

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    I'd go with the 340. I have a 28" draw and 70# draw weight and shoot a 340 FMJ cut to 27", which is pretty short and makes the arrow act more stiff. I put a 50 grain insert inside and shoot a 100 gr broadhead. I have no issues tuning my arrows and broadheads, but it does seem like the stiffer arrows are a little less forgiving.
    Now therefore, please take your weapons, your quiver and your bow, and go out to the field and hunt game for me.
    Genesis 27:3 (NKJV)

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    I shoot Easton axis 300s with 50gr of brass and 100gr heads, so its similar to tdcour. My arrows are 28.5" long and I shoot 68lbs for comparison.

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    Whats your FOC ? I know in the hunting world we say 10 to 15% is a good range. I tend to have it at the higher end at 14%.

    Higher will give you better stability but nose dive quicker......lower will be better flight path but eratic flight.

    I think its important to also fold that into the spline discussion.
    Last edited by Slugz; 03-14-2018 at 09:40 PM.

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    I’m not sure on FOC. I need to check it.

    Here’s another question... if I’m shooting a 400 spine arrow, which is 400 @ 28” correct? If it was cut to 27” would it actually be more like a 385 spine? Just doing the math, that’s what I come up with. Is it that simple or is there more to it?

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    Quote Originally Posted by CoHiCntry View Post
    I’m not sure on FOC. I need to check it.

    Here’s another question... if I’m shooting a 400 spine arrow, which is 400 @ 28” correct? If it was cut to 27” would it actually be more like a 385 spine? Just doing the math, that’s what I come up with. Is it that simple or is there more to it?
    I think you are on the right track. It is the deflection at that distance for a certain weight. I don't know if it is quite that simple of math. Deflection is calculated with PL^3/48EI in this case.... so the length is cubed.... so just a rough calculation... maybe... 358spine.

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    fyi, The 358 spine that I calculated would be the 28" long equivalent to your poundage. I think.

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    Not sure on the exact calculations, but yes, you would be going stiffer. Never thought to actually calculate the stiffness change though. I'd be interested to see how stiff my arrows are with the shorter length then the heavy weight up front. Heck, maybe they stay the same and offset each other.
    Now therefore, please take your weapons, your quiver and your bow, and go out to the field and hunt game for me.
    Genesis 27:3 (NKJV)

 

 
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