Arrow tuning & FOC

Kbhillhunter

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Wondering if an arrows FOC or length could impact how well it flies / tunes?

I'm in the process of switching arrows right now. My old arrows are 32.5" long, 525gr, and approx 10% FOC. The new arrows I'm using are also 525gr but they are 31.5" and approx 15% FOC. I used a spine program (spinal tap) and punched in all the specs of my new arrows and it seems like they should check out on paper.

So far they seem to be shooting pretty good but I havent tried broadheads or shot much beyond 20 yards yet. I had to do a little retuning at first, but i assumed that was because my bow was tuned for broadheads with my old arrows, so I was expecting that.
 

Mighty Mouse

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Shortening an arrow stiffens its dynamic spine. FOC isn't an independent variable that can be directly manipulated; it's the consequence of point weight, tail weight, shaft weight, and shaft length. The information you gave isn't enough to determine what (if any) adjustments might be necessary to get your new arrows to fly like your old arrows. If they both produce the same dynamic spine reaction, no adjustment would be necessary.
 

N2TRKYS

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I did alittle testing last summer with draw, arrow weight, and increases in FOC. I also tried a couple different brands of arrows, but all were the same length. I didn’t notice any changes in arrow flight. I didn’t have to retune my bow, either. All I did was bottom out my limbs in my limb pockets to increase the poundage.

Good luck and happy testing.
 
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Kbhillhunter

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Im shooting 60lbs at 31.5" with a 338 IBO

Both my old arrows and new arrows are a 250 spine. Old arrows at a 10.5 GPI and I was shooting with 150gr up front (50 insert and 100 tip). New ones have a lower GPI of 9.7 I think, and I cut it back 1". Using 100gr inserts with 100gr tips. Both arrows have standard 2" blazers and same weight nocks.

I was shooting at 40 yards tonight with field tips and was getting some decent groups. Other variables I'm dealing with: recently switched from a wrist release to a thumb trigger, and just general rustiness from taking a few months off. So thinking any inconsistency could be more due to form.
 
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Kbhillhunter

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So many guys F themselves by focusing on FOC and ignoring other aspects that are much more important.
What would you say are the pitfalls of focusing on FOC? For me it was secondary, I was mostly just trying to maintain my arrow weight so I could maintain the same pin gaps. I'm just trying to understand what I should look for to see if it's flying the way it should.
 

Billy Goat

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What would you say are the pitfalls of focusing on FOC? For me it was secondary, I was mostly just trying to maintain my arrow weight so I could maintain the same pin gaps. I'm just trying to understand what I should look for to see if it's flying the way it should.

Generally it's things you give up chasing foc. Some arrows it's extremely difficult to get a high foc. Some it comes naturally. It comes down to how long the arrow is.

Did you actually determine your foc or did the program you are using determine it? It's hard to get 15% with a 31.5" arrow. I have seen several programs be incorrect.

If your old arrows were below 10% and your new ones above 10% you might see some difference with broadheads. You get below 8% and it can be difficult tuning with broadheads. Once you are above 10% I think you are good and anything more won't change a thing.

Build an appropriate arrow and let your foc be where it is. It's easy for me to get it up there as I ave a shorter draw. You get arrows around 27" and its easy. Arrows past 30" get really difficult, takes a lot of point weight and you can run out of spine pretty quickly. You have some room since you are shooting 60, play if you want, it's how you will learn.


Keep in mind in playing with things once you put a broadhead on the front things can change. You will get more accuracy out of a weaker spine at distance, put a broadhead on and everything changes. So before you go all in make sure you can broadhead tune your setup.
 

5MilesBack

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Both 10% and 15%........and everything in between will tune and shoot just fine. If anything, I would expect the 15% to be more consistent.......but there are other variables that come into play with tuning instead of just FOC.

I was shooting GT Kinetic XT 200's cut to 30" at 75lbs and almost 33" draw and TAW of 520gr with 141gr total up front. Low FOC but they shoot great. I've been looking for a tougher arrow so just recently have been playing with some Victory RIP TKO Elite 250's at the same 30" but with 200gr up front to get them closer to my original arrow weight. They're coming in at 496gr. Much higher FOC and much weaker dynamic spine, but so far they're shooting great as well. If anything, I would expect my new dynamic spine to affect tuning and shooting over FOC.

I also tried 225gr up front to get them even closer to 520gr and they came in at 521gr. And even though they BH tuned really well......they seemed to be a little more twitchy in consistency. So I think I'll stick with 200gr up front.
 

MattB

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What would you say are the pitfalls of focusing on FOC? For me it was secondary, I was mostly just trying to maintain my arrow weight so I could maintain the same pin gaps. I'm just trying to understand what I should look for to see if it's flying the way it should.
I do not know what shaft you move from and to, but it is very likely that the new shaft will be less durable than the old.

Even Ashby says the arrow integrity is more important than FOC, but many casual disciples overlook that to their detriment.
 
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