# Spine choice for arrows with heavier FOC?



## Apohlo (Feb 18, 2013)

Hey bud, welcome to the world of arrow setup. In your case, it normally makes sense to bump up the arrow spine with the addition of a 100gr insert, but to be more accurate, you should go off of your current bow setup to match your dynamic spine value.

If you post up your bow info (model, draw length, draw weight, etc) I can run some numbers for you through my OT2 software! Hope this helps


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## Gutsdozer (Mar 23, 2014)

Apohlo said:


> Hey bud, welcome to the world of arrow setup. In your case, it normally makes sense to bump up the arrow spine with the addition of a 100gr insert, but to be more accurate, you should go off of your current bow setup to match your dynamic spine value.
> 
> If you post up your bow info (model, draw length, draw weight, etc) I can run some numbers for you through my OT2 software! Hope this helps


2015 Hoyt Nitrum 34, 61 lb. draw weight, 29" length. #2 cam module E. I was thinking about going with the 100 grain insert. This might be a bit over aggressive but it just seems like the more FOC I have the better my groups get. A 50 grain insert would probably be all I would need in actuality. I understand there has to be a point of diminishing returns also. Of course I have no idea what where that point is. If I loose too much speed it wont do any good to throw a log at 30 fps...


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## JF from VA (Dec 5, 2002)

You can use this calculator to play around with FOC values:

https://www.goldtip.com/calculators.aspx


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## Apohlo (Feb 18, 2013)

With your bow, shooting roughly a 28" arrow with a 125gr point, your optimal spine is .3355, very close to the .340 spine of your hunting arrows. Change that to a 100gr insert, and your optimal spine is .2997, very close to a .300 spined arrow. 

That extra 85 or so grains will get you an extra 5 or 6% FOC, making you hit somewhere in the 19-21% range! 

I personally would make that switch, but it's up to you!


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## Gutsdozer (Mar 23, 2014)

Apohlo said:


> With your bow, shooting roughly a 28" arrow with a 125gr point, your optimal spine is .3355, very close to the .340 spine of your hunting arrows. Change that to a 100gr insert, and your optimal spine is .2997, very close to a .300 spined arrow.
> 
> That extra 85 or so grains will get you an extra 5 or 6% FOC, making you hit somewhere in the 19-21% range!
> 
> I personally would make that switch, but it's up to you!


If I go with a 29" arrow that will weaken the spine right? Also, I see you have DCA arrows in your sig. At the moment I am using the Ecohunter arrows (350 spine). Any advice on arrow brands when it comes time for me to buy more? Can't spend a ton of money so a middle of the road arrow is what I usually look for. I know the shop I go to liked Easton and their off brands. The DCA arrows have actually been pretty to aside from me messing them up on occasion.


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## Apohlo (Feb 18, 2013)

Yes, however the inch would not affect the spine enough to stay with the 340's. I used to shoot the hunters, and they were a great arrow for the price, but I recently custom built some footers for axis 340 arrows and have decided to stick with them! I'm really liking the decreased diameter while being able to stay with the standard size points and broadheads.


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## Gutsdozer (Mar 23, 2014)

I just downloaded the trial of OT2. A bit confusing right now. Especially since I have now idea what kind of cam the nitrum has. I read somewhere to use select the "Use Mfg IBO" tab. Does this mean you have to setup the "equipment" section of the software?


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## Apohlo (Feb 18, 2013)

I would use that setting, Tess. Before using the program,though , you will want to setup your profile through the equipment tab. Input your bow, arrows, nock, and specs. You can then go right to the spine matching tab and change numbers around too match your dynamic spine to your optimal spine. It will take a little while to get used to it, but once you do, it's a very useful software!


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## [email protected] (Feb 23, 2004)

> Does this mean you have to setup the "equipment" section of the software?


You should. Then you can save your work in a user record to re-load next time you use the program.

On the MySetup tab, there is a Database Selection sub-tab. You can pick your setup from the 5 databases..Bow, Sight(not needed for spine matching), Shaft, Fletching, and Nock.

Pick your gear. Click the Apply button for each selection. "Apply"ing your picks sends your selections to the main MySetup form..where you can fine tune with DL, DW, etc. 

When you select a bow, you first need to pick the model year and then click the Load Year button prior to selecting the Brand and Model. 

When you enter Shaft Length, the program wants just the raw shaft material length..no nock, bushing, point insert.


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## Govtrapper (Mar 24, 2012)

Tagged to reread again


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