FOC increase

[Mudslinger]

JimboB, put some data up here on your bow, draw weight, and total arrow weight you are looking for.

[Loneaggie]

I shoot for less than 7gr/#, but I get my FOC by using the lightest gpi arrow I can get that will stand up to putting the biggest brass insert into it I can. Then I make sure I have no wraps etc on the back. Selection is limited in a 300 spine though if you shoot 70# and have a decent DL.

[Stick'n'String]

I'd visit with muddy as well. I asked him a ton of questions and he was very helpful and answered all my questions. I'll be in the market for new arrows soon and I'm looking to build a heavy arrow with a high FOC.

[JimboBurnsy]

JimboB, put some data up here on your bow, draw weight, and total arrow weight you are looking for.

I shoot a Mathews MR8 set for 70# @ 31". About the lightest I can build an arrow with a 100 grain point and not be underspined is 465 grains or so, maybe 450. I can get away with a 125 grain head on an arrow with .300 deflection, but my groups open up a little so I don't push it too much.

I could always back the poundage off and shoot arrows that aren't quite so stiff, but I like pushing a 580 grain arrow to 260 fps...

If I want FOC, I'm probably looking at super stiff Grizzlystiks and a completed arrow cost north of $200/dozen.

[muddyfuzzy]

I shoot a Mathews MR8 set for 70# @ 31". About the lightest I can build an arrow with a 100 grain point and not be underspined is 465 grains or so, maybe 450. I can get away with a 125 grain head on an arrow with .300 deflection, but my groups open up a little so I don't push it too much.

I could always back the poundage off and shoot arrows that aren't quite so stiff, but I like pushing a 580 grain arrow to 260 fps...

If I want FOC, I'm probably looking at super stiff Grizzlystiks and a completed arrow cost north of $200/dozen.

can get you done for under 150 easy.

[JimboBurnsy]

can get you done for under 150 easy.

You've piqued my interest, muddy...

[Mudslinger]

OK Muddy, spill the beans.

[hogdaddy]

my arrow, gt series 22 (300 spine) 27 ⅜ valley of nock to end of carbon, 20 gr insert slick trick xbow trick 150 or fp. cap dip or wrap 3 rayzr feathers. around 406 gr. & 19.4 FOC seems people get all freaked out over a .22 series shaft. marketing hype works. betting lots of us never saw 23 24 25 and up aluminums zipping through animals.
every arrow ever launched is an engineering compromise FOC is attained by using a stiff/light shaft and moving weight forward. find me a stiffer lighter one and I'll try it. add a 110 gr brass insert an you have a hog slammer.

[muddyfuzzy]

OK Muddy, spill the beans.

no beans, just arrow building. I have always been fascinated by the terminal performance of an arrow and I have done a lot of experimentation trying to find that perfect build........... there is not one there are only perfect arrows for certain situations. I just ask people what they want out of an arrow and try to give them what they ask for. its pretty easy to build a high (18+%) FOC arrow, trying to fit in the spine and where the weight ends up on the shaft is the tricky part.

you know as much; if not more, about the subject than most folks so I cant tell you anything you don't already know. but like I said earlier, most people are "average" hunters so they really benefit from as forgiving of an arrow as possible. if we keep it quick, of decent grains per pound of draw and try to get the most FOC possible we can build that arrow. it becomes a little more tricky for the long draw shooters but guys running around with 26-28" draw lengths can have some amazing arrows specs and likewise performance.

of all the folks I've built arrows for the average FOC increase is around 4.5%, that is a noticeable increase. if you have been shooting a 390 grain arrow with 11% FOC then tie on a 430-450 grain arrow sporting 16% you will know the difference the first time that arrow hits your target. personally I would focus more on broadhead design rather than arrow physics if penetration was paramount. guys like it because it keeps the speed up, hits very hard, penetrates well and is generally more forgiving and easier to tune.

[enewman]

Ok how do you decide what spine. I've been working a while now on that. I've had some good results out to 30 ft. Then it goes to crap. All me, my grip is bad. But I can take a 340 spine and it shoots good with total of 250 gn up front. That arrow is very weak according to ontarget. Same as my 300 spine. Around 315 total up front. Weak on program.

I like to stay above 19%. Do I think it's needed no. And around 500 to 575 mark. The weight is mainly just to keep the bow as quite as possible. Is that needed no. I think the arrows your building at that 450 mark are great. I just like the sound difference.

[Mudslinger]

I have a very weak spine also on my set up with 250 grains total up front (GT 75/95 @ 28" with 150 grains added insert weight and 100 grain point, 560 total grains), but they still shoot fine. It gets really tricky finding a spine that is less than .300, not many out there. This would be for building a heavier than normal arrow with a high FOC, such as one I am building for a Cape Buffalo hunt. Just not enough need for the very stiff spine as most do not need one. When you start looking at .275. .250 and .225 spine, it can get really expensive testing at the cost of these arrows.

[enewman]

I have a very weak spine also on my set up with 250 grains total up front (GT 75/95 @ 28" with 150 grains added insert weight and 100 grain point, 560 total grains), but they still shoot fine. It gets really tricky finding a spine that is less than .300, not many out there. This would be for building a heavier than normal arrow with a high FOC, such as one I am building for a Cape Buffalo hunt. Just not enough need for the very stiff spine as most do not need one. When you start looking at .275. .250 and .225 spine, it can get really expensive testing at the cost of these arrows.

I always thought you where crazy. No way that weak of spine will shoot from your bow. But I'm doing the same now. So does that mean I'm crazy.

[Stick'n'String]

I have a very weak spine also on my set up with 250 grains total up front (GT 75/95 @ 28" with 150 grains added insert weight and 100 grain point, 560 total grains), but they still shoot fine. It gets really tricky finding a spine that is less than .300, not many out there. This would be for building a heavier than normal arrow with a high FOC, such as one I am building for a Cape Buffalo hunt. Just not enough need for the very stiff spine as most do not need one. When you start looking at .275. .250 and .225 spine, it can get really expensive testing at the cost of these arrows.

Well when you find a good .250 spine with a high FOC let me know because I need a 250 spine for the setup I want. The FMJ dangerous game's GPI is too high to get a good FOC in my opinion. And I don't trust GT spines after seeing enewman's post. Also my dad had very poor groups out of his competition now when shooting GTs. He switched back to his other arrows and the groups tightened up

[enewman]

It's not going to be easy to find a 250 spine. I know I bought some arrow dynamic stingers. 250 spine. Out of twelve. Three were .280 to .290. The rest where around .305 not a bad arrow just I was wanting the 250 spine. I just don't see how they can make a stiff spine and still be lite in weight.

[Frederick D. Be]

Yes tuning is a major factor in this. So is correct spine. We all can get a weak arrow to shoot bullet holes. Flight is great. But penetration is bad. Then we start blaming the broadheads. But what is happening is that when the arrow makes contact with the animal the weak arrow will flex which now causes the shaft to hit the animal side ways. This is what causes bad penetration. Easy to see. Get a tuff target. Shoot a stiff arrow in to it and watch the shaft. Then shoot a weak arrow and watch. It looks like a antenna after you bent it over and let go.

This is a very good post. Dynamic spine must be taken into account when adding weight at the front of the arrow. For example, my friend wanted to increase to 125 grains up front with the same arrow...same length. We could not get it to tune worth crap. Back to the 100 gr and it tuned extremely well. Also, by increasing the FOC and moving the balance point forward, you will, assuming you have the correct spine and I would rather be over spined than under spined, have a more efficient arrow because when it hits the intended target there is less of the arrow between the balance point and the tip to flex causing less flexing...unless you are under spined. Good post here. Cheers!
Fred