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Author Topic: FOC issue.  (Read 6916 times)

Offline Smossy

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FOC issue.
« on: July 01, 2013, 04:22:58 PM »
I finally just did the math/measurements on the correctly cut length of arrow that I intend on hunting with, With Field Points my FOC is around 9.1666% and with Broadheads my FOC is around 8.870%

Not sure what all that means but I imagine its supposed to be alittle higher, Im looking for around 12% and not sure where to go from here, to add weight to the front? To the back? What kind of things do you guys usually add to play with the balance, etc...

Goldtip XT Hunter's 8.2gpi - Length @ 28.750" from nock throat to tip insert. 7/8inch+ for FP and for those math guru's BH is 1 inch.
- Balance came into around 17.750 inches from nock throat to balance point with the FP - and 18.250 with the BH.
Im using 100 grain tips. 2inch blazer vanes set 5/8"inch In from the very end of the arrow, not the nocking point.

Hope thats enough information to have someone help me out. Im not liking the low FOC, it seems very unforgiving and probably lacks penetration. 
« Last Edit: July 01, 2013, 04:31:42 PM by Smossy »
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Offline demontang

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Re: FOC issue.
« Reply #1 on: July 01, 2013, 05:29:12 PM »
How much weight are you pulling? What spine are your arrows? Id guess your shooting 400spine and pulling 55-60lbs?  Ive been playing with foc and flight of my broadheads lately, 9% doesnt seem to be right, they seem to fly better with 12%. I see on gold tips sight you should be in the 10% range, you can do a few things to change your foc but it affects the spine of your arrow. You can add weight to the front of your arrow and get the foc up but loose spine doing this,.My beman ics hunter pro are about 10% and my axis are 12% and the axis fly a little better..  Radsav should chime in I know he is deeper into this then me and can get you a better answer.

Offline bowhunterforever

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Re: FOC issue.
« Reply #2 on: July 01, 2013, 05:39:59 PM »
Since this topic came up, How do check what you foc is? Curious what mine is.Thanks
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Offline hughjorgan

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Re: FOC issue.
« Reply #3 on: July 01, 2013, 05:51:42 PM »
Since this topic came up, How do check what you foc is? Curious what mine is.Thanks

http://archeryreport.com/2010/09/arrow-foc-basics-calculate/

Offline hughjorgan

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Re: FOC issue.
« Reply #4 on: July 01, 2013, 05:59:15 PM »
I finally just did the math/measurements on the correctly cut length of arrow that I intend on hunting with, With Field Points my FOC is around 9.1666% and with Broadheads my FOC is around 8.870%

Not sure what all that means but I imagine its supposed to be alittle higher, Im looking for around 12% and not sure where to go from here, to add weight to the front? To the back? What kind of things do you guys usually add to play with the balance, etc...

Goldtip XT Hunter's 8.2gpi - Length @ 28.750" from nock throat to tip insert. 7/8inch+ for FP and for those math guru's BH is 1 inch.
- Balance came into around 17.750 inches from nock throat to balance point with the FP - and 18.250 with the BH.
Im using 100 grain tips. 2inch blazer vanes set 5/8"inch In from the very end of the arrow, not the nocking point.

Hope thats enough information to have someone help me out. Im not liking the low FOC, it seems very unforgiving and probably lacks penetration.

How do you end up with a different FOC, if your field point is 100 grains and BH is 100 grains the FOC should be the same....

Are you shooting 3 fletch or 4? Vanes or feathers? You can lighten up the back end to give yourself greater FOC depending what you do.

You can build arrows with brass inserts to add weight up front, but you will have to probably buy new arrows...

As has been stated you can bump your field tips/ BH to 125 grains from 100, this could pose a problem if you are borderline on spine for your setup. You should be able to look up on gold tips website if a heavier head will work.

Offline dawn2dusk

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Re: FOC issue.
« Reply #5 on: July 01, 2013, 06:59:02 PM »
Gold tip offers insert weights you can add. 10 and 20 grains and fairly cheap too. Just another option for you. Pretty easy way to adjust FOC
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Offline Smossy

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Re: FOC issue.
« Reply #6 on: July 01, 2013, 10:37:49 PM »
How much weight are you pulling? What spine are your arrows? Id guess your shooting 400spine and pulling 55-60lbs?  Ive been playing with foc and flight of my broadheads lately, 9% doesnt seem to be right, they seem to fly better with 12%. I see on gold tips sight you should be in the 10% range, you can do a few things to change your foc but it affects the spine of your arrow. You can add weight to the front of your arrow and get the foc up but loose spine doing this,.My beman ics hunter pro are about 10% and my axis are 12% and the axis fly a little better..  Radsav should chime in I know he is deeper into this then me and can get you a better answer.
62lbs and a 400 spine, yes sir. I texted Radsav about the issue but hes slow on phones so you guys will have to do for now :tup: So a 125 grain BH should help?
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Offline Smossy

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Re: FOC issue.
« Reply #7 on: July 01, 2013, 10:38:30 PM »
Since this topic came up, How do check what you foc is? Curious what mine is.Thanks

http://archeryreport.com/2010/09/arrow-foc-basics-calculate/
Exact website and math I used also. :tup:
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Offline Smossy

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Re: FOC issue.
« Reply #8 on: July 01, 2013, 10:39:34 PM »
I finally just did the math/measurements on the correctly cut length of arrow that I intend on hunting with, With Field Points my FOC is around 9.1666% and with Broadheads my FOC is around 8.870%

Not sure what all that means but I imagine its supposed to be alittle higher, Im looking for around 12% and not sure where to go from here, to add weight to the front? To the back? What kind of things do you guys usually add to play with the balance, etc...

Goldtip XT Hunter's 8.2gpi - Length @ 28.750" from nock throat to tip insert. 7/8inch+ for FP and for those math guru's BH is 1 inch.
- Balance came into around 17.750 inches from nock throat to balance point with the FP - and 18.250 with the BH.
Im using 100 grain tips. 2inch blazer vanes set 5/8"inch In from the very end of the arrow, not the nocking point.

Hope thats enough information to have someone help me out. Im not liking the low FOC, it seems very unforgiving and probably lacks penetration.

How do you end up with a different FOC, if your field point is 100 grains and BH is 100 grains the FOC should be the same....

Are you shooting 3 fletch or 4? Vanes or feathers? You can lighten up the back end to give yourself greater FOC depending what you do.

You can build arrows with brass inserts to add weight up front, but you will have to probably buy new arrows...

As has been stated you can bump your field tips/ BH to 125 grains from 100, this could pose a problem if you are borderline on spine for your setup. You should be able to look up on gold tips website if a heavier head will work.

The broadheads are longer than the field points :dunno:  Maybe I screwed up somewhere, Im not great with numbers.
3 Fletch 2" Blazer vanes. and Ive mastered removing inserts.

https://www.youtube.com/watch?v=dIto4WoZhjQ
« Last Edit: July 01, 2013, 10:46:18 PM by Smossy »
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Offline hughjorgan

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Re: FOC issue.
« Reply #9 on: July 01, 2013, 10:53:09 PM »
Well do your broad heads shoot true with the current FOC? I would think that 125 grain tip should put you over 10% FOC.

If you want to lighten up the back of the arrow get a hold of some rayzr feathers, they only weigh 2 grains vs the blazer being ~6 grains if I remember correctly.

Offline Smossy

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Re: FOC issue.
« Reply #10 on: July 01, 2013, 10:57:07 PM »
Well do your broad heads shoot true with the current FOC? I would think that 125 grain tip should put you over 10% FOC.

If you want to lighten up the back of the arrow get a hold of some rayzr feathers, they only weigh 2 grains vs the blazer being ~6 grains if I remember correctly.
Would it help If I changed everything and went with a 340 spine? Elk247 helped me out with a 6 pack of 340 spiners at 9.2gpi I think it was.
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Offline hughjorgan

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Re: FOC issue.
« Reply #11 on: July 01, 2013, 11:04:21 PM »
Well do your broad heads shoot true with the current FOC? I would think that 125 grain tip should put you over 10% FOC.

If you want to lighten up the back of the arrow get a hold of some rayzr feathers, they only weigh 2 grains vs the blazer being ~6 grains if I remember correctly.
Would it help If I changed everything and went with a 340 spine? Elk247 helped me out with a 6 pack of 340 spiners at 9.2gpi I think it was.

Don't know, I try a heavy fp/bh to get your desired FOC first.

Did you figure out your FOC on the .340s?

Offline Smossy

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Re: FOC issue.
« Reply #12 on: July 01, 2013, 11:18:37 PM »
Well do your broad heads shoot true with the current FOC? I would think that 125 grain tip should put you over 10% FOC.

If you want to lighten up the back of the arrow get a hold of some rayzr feathers, they only weigh 2 grains vs the blazer being ~6 grains if I remember correctly.
Would it help If I changed everything and went with a 340 spine? Elk247 helped me out with a 6 pack of 340 spiners at 9.2gpi I think it was.

Don't know, I try a heavy fp/bh to get your desired FOC first.

Did you figure out your FOC on the .340s?
Not yet, I think the foc came to about 9.8%

Maybe my math is wrong.
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Offline Crunchy

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Re: FOC issue.
« Reply #13 on: July 01, 2013, 11:27:29 PM »
I've never checked my arrow FOC and the dead elk didn't either. Dont beat yourself up over minor details. Correct spine is more important.

Offline jgrimes

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Re: FOC issue.
« Reply #14 on: July 01, 2013, 11:43:53 PM »
You can cut your arrow down so that your FP/BH is just in front of your launcher arm/biscuit. This effectively stiffens your arrow, but it also improves your FOC. I shoot 63 lbs with a 350 spine arrow and a lot of weight up front (~15%). If the BH you like is offered in a 125 gr option that would be a good way to achieve your goal. Cutting your arrows down and adding more weight up front could possibly get you close to the same arrow weight you have now, so that you won't need to adjust your sight much. I enjoy this site http://www.backcountrybowhunting.com/articles/calc/ give it a look.
JG

 


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