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Hi guys. According to Gold Tip's chart, I'm right on the edge of a 340 or 400 spine. Which way should I go? I'm a 27" draw with 65lb draw weight. Do I lose or gain anything by going with the 340 over the 400?
 

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Typically you want to go to the stiffer side if your on the edge. How long are your arrows?
 

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I'll bet 340s will tune much better. I know it's not a perfect comparison, but I shoot 340s out of my 60 lb bow set at 27.5 " draw length, and arrows cut at 27.5." They fly great.
 

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"Compound Bows - With Release Aid
Note: With a compound bow and release aid it is acceptable to use a shaft that is stiffer than indicated on the selection chart. This is particularly true if you want to shoot a larger diameter shaft for target and 3-D archery. When in doubt, choose a stiffer arrow shaft."

off the GT arrow selection chart
 

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340 will be much better for your setup.
 

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Generally a stiffer spine is a heavier arrow. With short draw and low poundage going with the stiffer spine will slow you down.

I shoot 60 and 65 lb bows at 28" draw (arrow length of 27 1/4" ) and have no trouble tuning with 400 spine on MOST of my bows, also with 100 gr points. A couple of my strong cam hybrids require a 350-340 to tune.
I was taught to shoot as light a spine as you can. But I've only been shooting for 36 years. So what do I know? I know that it works for me, but due to varying tuning abilities it may not work for everyone.

But if you have to go stiffer to get a straight arrow flight., why stop at 350? Why not buy 300 or even 250 spine? Why not just stick a nock on a piece of rebar? If stiffer is better........

Here's another note......Arrows are tested for spine at a length of 28 ". The more you cut off the arrow below 28" the stiffer the spine becomes. If you add an arrow wrap you are adding stiffness to the spine. You can actually turn a 400 into a 350 with the right length and accessories. In other words, your question leads to more questions.....all affecting the proper answer to your question.

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I would go with the .340 spine at 27-5/8" and 65#...

Spine is spine...adding 100 grains extra up front doesn't change spine it requires that a shaft with a stiffer spine be selected to accommodate the extra weight. Shortening the arrow doesn't change spine either...it allows an arrow with a weaker spine to be selected because the physical distance between the opposing forces (bowstring and arrow point) is less. Kinda like selecting a floor joist to carry a load...a 16 ft span might require a 2x10 to carry a 200lb load while a 2x4 over a 4ft span might carry the same load.
 

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Generally a stiffer spine is a heavier arrow. With short draw and low poundage going with the stiffer spine will slow you down.

I shoot 60 and 65 lb bows at 28" draw (arrow length of 27 1/4" ) and have no trouble tuning with 400 spine on MOST of my bows, also with 100 gr points. A couple of my strong cam hybrids require a 350-340 to tune.
I was taught to shoot as light a spine as you can. But I've only been shooting for 36 years. So what do I know? I know that it works for me, but due to varying tuning abilities it may not work for everyone.

But if you have to go stiffer to get a straight arrow flight., why stop at 350? Why not buy 300 or even 250 spine? Why not just stick a nock on a piece of rebar? If stiffer is better........

Here's another note......Arrows are tested for spine at a length of 28 ". The more you cut off the arrow below 28" the stiffer the spine becomes. If you add an arrow wrap you are adding stiffness to the spine. You can actually turn a 400 into a 350 with the right length and accessories. In other words, your question leads to more questions.....all affecting the proper answer to your question.

REMEMBER the ALAMO!!!
I know you said you have been doing for 36 years. So I mean no disrespect. But haha you new the but was coming.

Yes static spine is done at 28 inches with a 1.94 lb weight. But static spine on an arrow never changes unless it's broke. When shooting the arrow it has a dynamic reaction. This is what changes when changing length of a shaft or tip weight or what ever. And yes with a compound bow being shot with a release he could shoot and tune a 200 spine arrow. That is the good thing about compound with a release you can tune a wide range of spines.

To the op. Go with the .340 spine. It will tune just fine
 

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I guess archery science has changed since you guys were born.... Good luck with the new science!!


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I know you said you have been doing for 36 years. So I mean no disrespect. But haha you new the but was coming.

Yes static spine is done at 28 inches with a 1.94 lb weight. But static spine on an arrow never changes unless it's broke. When shooting the arrow it has a dynamic reaction. This is what changes when changing length of a shaft or tip weight or what ever. And yes with a compound bow being shot with a release he could shoot and tune a 200 spine arrow. That is the good thing about compound with a release you can tune a wide range of spines.

To the op. Go with the .340 spine. It will tune just fine
So hang that 1.94 weight on a shaft cut to 10" and see if the deflection is the same........sorry.


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i am shooting the gt pro 400
27.5 draw weight, 60lbs, 100g tip and they are flying great!
 

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So hang that 1.94 weight on a shaft cut to 10" and see if the deflection is the same........sorry.


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If you adjust the weight for the correct measurement of that length it will be the same.

You have been around long enough to remember the amo method. 26 inches with a 2 lb weight. Then they went to the ibo method 28 inches with a 1.94 lb. it's a static measurement. I have not set down to calculate up. But the shorter the arrow you need more weight. It's just a measurement. And static never changes. But just say it's linear. That would mean if 2 lbs is for 26 inches and 1.94 is for 28 inches. Then it's 1.97 for a 27 inch. So your 10 inch arrow is going to take a 2.48 lb weight. Now this is just numbers cause I'm sure it will be a little more then that.

This is not my opinion this is how it works. Look it up. Static spine is static spine. It will not change ever.
 

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That is deflection...not spine. Spine is defined as deflection AT 28" and only 28".
Agreed, but deflection is what you are tuning with.... Not some company's spine rating. You can put more weight on the front of a stiffer spine and bring it down to the same deflection as a lower spine rated shaft. So, unless you are shooting a 28" shaft with no point weight or other adornments on the shaft, what a company rate the spine as doesn't end up meaning all that much. It is just a starting point.


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If you adjust the weight for the correct measurement of that length it will be the same.

You have been around long enough to remember the amo method. 26 inches with a 2 lb weight. Then they went to the ibo method 28 inches with a 1.94 lb. it's a static measurement. I have not set down to calculate up. But the shorter the arrow you need more weight. It's just a measurement. And static never changes. But just say it's linear. That would mean if 2 lbs is for 26 inches and 1.94 is for 28 inches. Then it's 1.97 for a 27 inch. So your 10 inch arrow is going to take a 2.48 lb weight. Now this is just numbers cause I'm sure it will be a little more then that.

This is not my opinion this is how it works. Look it up. Static spine is static spine. It will not change ever.
So you are agreeing that things change with the length of the shaft? You may be on the verge of understanding where I am coming from......


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I know guys that tune their arrows to their bow.....after basic bow tuning. They do this by starting with a longer length shaft and slowly shorten the shaft until they have reached optimum flight. That is just another way to up your accuracy...


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