Arrow Spine Selection and Tuning Help

Eprevost_tec

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Joined
Jun 25, 2018
Messages
60
Hello all,

I have had a couple of very successfull years and have taken the leap into archery. Back in Octover I purchased a new bow and through Octover to January was able to get some instruction and lessons on how to shoot properly. I shoot about 20 shots every day and have been able to increase my draw weight over that time to the bows current max draw weights of 65 lbs (Mathews VXR). I feel that I still have some strenght to build, but feel good about the bow and hunting with the current setup.

Recently I have been working on building and testing a good arrow and broadhead setup. I like the Easton Axis arrows and will be sticking with them moving forward. Here is where my problem comes in.

Based on the arrow charts, with a total arrow lengh of 27 inches and a point weight of 116 gn (16 gn HIIT insert and 100 gn point), I get perfect bullet holes through paper. Both fletched and bare shaft are awesome and flying perfect.

In an attempt to increase my arrow weight, and FOC, I am looking to increase my shaft, insert and point weight. Again, using the arrow chart, I have a total point weight of 200gn (75gn HIIT insert and 125gn point), I get and arrow with a 340 or 300 spine. I purchased two shaft of each spine for some bare shaft and fletched arrow testing. I installed the inserts and hit the paper board. With the setup I mention, I am getting strong tail left tears. Based on my research this means a spine that is too weak. What is confusing to me is that I get the same tears with the 340 and 300 spike arrows.

Based on the 400 spine arrow tests with the lower point weight, I know the bow, rest, etc are all in tune. My guess is that I have ruled out a bow problem. So now I am just left with and arrow issue??

Can anyone help me understand what is going on here. Why would I be getting such a tail left tear on both spines. Should I not at least see a tail right tear with the 300 spine since I should be over spine in that case??

Ultimately I am chasing a 450+ arrow weight, so any help in that department, considering I am working with a 27inch arrow would be appreciated.

Thanks

Eric
 

p_ham

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Jul 6, 2017
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Fallon, NV
You'll have to do some tuning. Think of it as shooting different ammo in your rifle.
Even if the arrow is spined correctly the paradox of the arrow won't be the same. You could also be torquing your bow so make sure you have a relaxed grip.
 

pojoaque40

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Apr 28, 2019
Messages
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Location
Santa Fe, NM
You'll have to do some tuning.

Agreed. The beauty of the modern compound is its simple and seemingly unlimited adjustability. I'll tune arrows to my trad gear; i tune my VXR to the arrows.

I'd buy the stiffer arrows and adjust your rest. If that doesn't solve it have a look at swapping the top hats. A perfect center-shot rest is ideal but i've never gotten bullet holes from it. I use center-shot as a starting point.
 

Eprevost_tec

Member
Joined
Jun 25, 2018
Messages
60
Thanks,

Follow up question for you.

If my lighter arrows are shooting bullet holes, and I tune for the heavier arrows, will it not then be out of tune for the lighter arrow??

I though that if the arrow was leaving the bow square and true, then all arrows should do the same regardless of weight??

Thanks
 

N2TRKYS

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Jul 26, 2016
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I went from an arrow weighing 367 grains all the way up to 480 grain and didn’t do anything to my bow. The only thing I did was max my poundage out to get a high speed.
 

pojoaque40

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Apr 28, 2019
Messages
125
Location
Santa Fe, NM
There are more variables than just weight and static spine involved. To get identical flight you'd need similar arrow setups, including dynamic spine, FOC, etc. I find that when i get my heavy arrows dialed my lighter ones are only a couple rest clicks away. For reference i shoot 28" 300sp black eagle deep impact, 575gn for elk and between 475 and 525 for pronghorn. I simply leave the arrow alone and swap out the BH.
 

N2TRKYS

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I tried weights of 367, 406, 437, 450, and 481. I used Gold Tip(400-300 spine) and BE Carnivore(300 spine) arrows. The foc varied a good bit between them, as well. I never moved anything, but my sights.
 

golfer

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Jul 20, 2010
Messages
1,444
I personally would not get hung up on the FOC aspect. I don't think you need an FOC of "x" to be able to hunt. Find what your bow likes and stick with it. Also, the tear with the two arrows may be you torquing the bow as well. Is your form correct?
 

LuketheDog

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Nov 29, 2015
Messages
3,418
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Sedalia, Colorado
Why are you fixated on 450gr and FOC? Your your arrows fly well, so maybe just be happy with where you're at.

...Or you could try this:

...Or you could switch to a heavier shaft, like a FMJ
 

Trbrincefield

New member
Joined
Jul 30, 2019
Messages
8
Location
Fresno, CA
Thanks,

Follow up question for you.

If my lighter arrows are shooting bullet holes, and I tune for the heavier arrows, will it not then be out of tune for the lighter arrow??

I though that if the arrow was leaving the bow square and true, then all arrows should do the same regardless of weight??

Thanks
It will most likely be out of tune for a lighter arrow.
 

Eprevost_tec

Member
Joined
Jun 25, 2018
Messages
60
Just to follow up, in the end, it was a shaft issue. I was able to get the 340 shaft arrows to tune perfectly, then shoot a 400 with a lighter insert and get the same bullet hole result.

Thanks for all the help and input.
 

Foggy Mountain

Active member
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Jun 10, 2021
Messages
173
Brother I know this is an old thread but God almighty people think you need crazy weight. Dr Ashby did a good thing but at the same time imo he way confused people. I’ve over hundred deer with 100-125 grains. Similar weight bow. The arrow didn’t even attempt to stay in the deer. I understand the styk guys looking at weight to add penetration, I’m one of em but still not overly crazy with it. Old school me used 125 gr head with 63lb recurve.
You’re initial set up was more than sufficient for most animals in this country. Stop giving yourself a headache unless you’re going for hippo

To answer your question, you can’t tune unless your form is perfect. You also must check it a various distance to make sure your read is correct.
 

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