Trad Gang
Main Boards => PowWow => Topic started by: bm22 on November 11, 2009, 08:35:00 PM
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i am shooting a 595gr arrow at 183fps with 58@29in. i have a 30.5% foc arrow, i have heard alot of talk about 20-25% but this seems like alot. i assume this is a good thing most seem to say more is better.
i am also shoot 175 abowyer wapiti broadheads with footed carbon/kevlar shaft. would you say they are a good combo?
plan to shoot deer and hogs!!! if i ever get a shot lol
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My uncle Jim was about 60%, I do believe.
I would think there is a line of diminishing returns in any tip weight to length. You must be shooting Balsa Wood to get 30.5% foc with 595 grain arrow. Are you sure you calculated correctly? Maybe my math is off a bit 8^) but that sounds like a high %.
I shoot about 18% FOC.
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George, I was thinking the same thing as I read his post. That's an extremely high FOC for a 595 grain arrow.
That's very good speed too, BTW.
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Abowyer wapiti. 175
steel insert. 125
goldtip insert. 15
alum footing. 15
total 330
kevlar arrow. 255
feather and nock. 10
595 ish
bareshafts perfectly. Plugging the total arrow lenght and balance point into a foc calculator gave me 30.5% idk how accurate the calculator is.
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One of the moderators is shooting a 29.5 inch arrow that is right at 30% FOC using Beman ICS Bowhunter shafts in 500 spine. So you are right in the same FOC range. I think that his arrows weigh more than yours do though.
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Where are you getting your kevlar arrows? Who is the manufacturer? Dr Ashby indicated in another post that 30% FOC dramatically increases penetration over 20%, etc... His updates should be coming out shortly and #6 is supposed to cover really high FOC.
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I shoot 420gns arrows that are a bit over 30%.Highest I have ever used because I don't want to get my arrow weight much heavier than it is.Seems to work just fine like other arrows do.I did not come up with that foc on purpose.Just what it worked out to shoot the 200gn broadhead I wanted to use on a shaft light enough to not finish out too heavy.
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Originally posted by Clay Walker:
Where are you getting your kevlar arrows?
I'll second that, where are you getting kevlar arrows...brand?
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I think he maybe means carbon.
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Carbon Express makes a Kevlar Arrow the Aramid KV guys.
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Ahh, I see...a carbon/kevlar composite. Kevlar by itself would suck as an arrow material but I can see it added, especially the outer layer to protect the carbon. Thanks Dave, I had no idea anyone on the market was adding kevlar.
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No problem JC. I have yet to try them but I know some compound guys who've had some real good results with them.
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Originally posted by bm22:
Abowyer wapiti. 175
steel insert. 125
goldtip insert. 15
alum footing. 15
total 330
kevlar arrow. 255
feather and nock. 10
595 ish
bareshafts perfectly. Plugging the total arrow lenght and balance point into a foc calculator gave me 30.5% idk how accurate the calculator is.
the foc % results don't seem right for the arrow specs given above. how are you calculating foc?
balance the arrow. measure the distance from the nock grove to the balance point. plug that number into the spreadsheet formula found HERE (http://www.tradgang.com/docs/arrow_calcs.xls)
FOC forumula ...
(nock groove to balance point distance) subtract (1/2 the arrow length), times that result by (100 divided by the arrow length)
fwiw, my arrow spex ...
beman ics 500 @ 29.25"
bohning nock
4" lo-pro 4-fletch
aluminum insert
internal footed weight tube
point (complete w/adpater)
total arrow weight = 665 grains
foc balance point = 23.3"
foc = (23.3-14.625)*(100/29.25) = 29.66%
holding bow weight = 55#
gpp = 12.09
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Rob,I was thinking exactly the same thing.My 30" arrows weigh 709 grains,have 409 grains up front and FOC is only 27 %,which is fairly high.
So these arrows are 409 upfront and 300 for the rest.
BM22's arrows are 330 front and 265 rear.That is a lower percentage of weight up front.I couldn't see what the actual arrow length is,for these but I don't see how they could be 30 %.I would guess,more like mid 20's.
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I balanced it on a knife, it was 26.5, from the throat of the nock to the balance point. The arrows are 32.5 in from thethroat of the nock to the end of the insert, i guess i lose a slight bit of foc if you measure out to the tip of the broadhead.
Foc( 26.5-16.25)*(100/32.5)=31.5%
do u measure to the insert or out to the tip of the broadhead, since broadheads are all different lenghts , for comparison purposes i assume it would be the insert. If not that would explain my higher than normal #.
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I just punched his numbers in the foc calc in the how-to section and it came up 31.54%
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You measured correctly.I worked these numbers out on paper,now having the arrow length etc.I came up with 31.5% also.That is a ton of FOC.You did everything right and I stand corrected.
I think your high FOC comes from the long arrow and super light shaft material.Getting great speed with it too.It should be a super efficient setup.Nice job.
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I'm shooting several hand loaded Big Game 100's that are from 816 grains to 1020 grains and 28% EFOC to 31.5% Ultra EFOC.
These arrows are not fond of stopping when faced with resistance.
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So BM22,what is the Kevlar shaft you are using?
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Originally posted by bm22:
I balanced it on a knife, it was 26.5, from the throat of the nock to the balance point. The arrows are 32.5 in from thethroat of the nock to the end of the insert, i guess i lose a slight bit of foc if you measure out to the tip of the broadhead.
Foc( 26.5-16.25)*(100/32.5)=31.5%
do u measure to the insert or out to the tip of the broadhead, since broadheads are all different lenghts , for comparison purposes i assume it would be the insert. If not that would explain my higher than normal #.
full length shaft is what done the quite high foc deed for ya.
for shaft length, i measure from the nock groove to the end of the shaft, not the end of the insert and definitely not the end of the point.
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Rob,
That is what I have found on my setups. Having a stiff enough arrow so that I can keep it full length allows for 28% EFOC right out of the box.
I am pulling 31ish inches anyway so there isn't much arrow left hanging out.
I can cut off 1/8 to 1/2 and bump FOC to 31%+ Ultra EFOC.
Measuring from nock groove to end of shaft is correct.
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i am shooting arrows by a small company named forge. they seem to be very strong arrows, i have only shot them for a short while, have done little stump shooting with them but i have shot several trees straight on and glancing shots and i haven't broken a shaft yet. and the guy i lease from has shot them for awhile and he is a dealer, he said they are the strongest arrows he has shot and that they are made with kevlar, they do not advertise the kevlar part on the website.
yes they are extremely light gpi, i pull 29 in and have several inches hanging over, i suspect that i could go down from 7.8 to 6.9 gpi arrows and cut them off and they would be plenty stiff then i could add the extra 31 grains to the front and get a 35-40% foc arrow. but they are pricey arrows so i got the ones i KNEW would work.
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Very interesting.They sure don't give any hints on their site,where a person can get them.Do you know any dealers that do mail order?
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bm22, are you shooting Slipstream 60's?
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Nope, extreme 50-70's, email him they will ship you some. I think the public cost is $110-120 a dozen
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Thanks.
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