muzzyman88

Buck, it seems to me that you are shooting an awefully heavy shaft out of that bow. How much weight you drawing? Anyway, I find that 12% or close to it works well for me, especially with a fixed blade head. I think it really helps give the arrow some direction. Looks to me that you might have to fix a boat anchor to the front of those to get them down. 125 grain should be pretty decent.

buckeye

OK a different question. If I want to account for the length can I do the following?

My shaft is 29 inches.
MY BH is 1 inch.

So could I say in my caluclations that my arrows are 30 inches and subtract 8 grains form my broadhead weight to make up the difference.

So instead of a 29 inch shaft and 100 grain tip could I say I have a 30 inch shaft and 92 grain tip???? Thanks

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Buck Magnet

Okay guys, let me see if I can answer some ????'s here.

I am shooting 28.25" GoldTip 3-D Pro 75/95 arrows. They weigh 8.9 grains per inch which means that a bare shaft weighs 251.425 grains. The insert and nock both weigh 15 grains apiece which is a total of 30 grains. Add that to the shaft and you get 281.425. I am using 3-4" Duravanes which weigh 8 grains a piece, for a total of 24 grains. Add that on and you get.... 305.425 without any b-head in it. Putting in a 125 grain b-head brings it up to 430.425 grains

My Bow is a 2004 BowTech Libert, 29.5" draw and 71# draw weight!

The first thing I did to get these measurements was....

1. Put a b-head on the arrow
2. Measure the length of the arrow (from groove of nock to tip of b-head)
3. Divide that number by 2 to get the center of the arrow
4. Balance the arrow and mark on the arrow where it balances with a pencil.
5. Measure the distance from the tip of the b-head to where the arrow balances
6. Subtract the distance that the arrow balanced from the center of the arrow
7. Plugged that into the calculater to get the FOC

I measured it according to this.... http://home.att.net/~sajackson/archery9.html

Elkcrazy8

BM ,Sounds correct to me. I get so involved in this stuff during the off season, that I will sit down and use up a tablet of paper in one night. Kinda wierd what a guy will do when he can't shoot. I hope that when you are aiming at your computer with your bow that you don't have an arrow in. You don't want to mess up a good arrow if the bow goes off.

CLOUD 9, MN

I'll bet you have vanes. Very simplily you can switch to feathers and I'll bet you'll be at 10 to 11.5%. With 100 grain tip and feathers maybe 12%

Good Luck!

TFOX

Navy,the reason that foc affcts penetration is simply that when the front end is too light and the arrow encounters resistance,the back end of the arrow will try to pass up the front.This kick will take the energy that the arrow has and direct it in a different direction.


This is why someone with a higher ke level can get by with less foc than someone with low ke imo.Ke is actually the energy in the arrow that allows the arrow to remain parallel to it's original position throughout it's motion.An arrow that flies straighter or has the ability to fly straighter will penetrate better.

TFOX

I also disagree with measuring foc to the font of the broadhead.When we are talking arrows and foc we are usually referring to spine and the aluminum broadhead will not spine the same as an arrow.Yes,mathematically it is correct to account for the broadhead length but not in archery.Atleast Easton doesn't reccomend measuring the broadhead and I tend to agree.

Straightarrow

I agree that feathers will increase the FOC, but lowering tip weight will reduce it, not increase it.



Buck Magnet, I'm shooting an almost identical setup and my fixed blade broadhead flight is very good. Regardless of whether you measure to the tip of the broadhead or the end of the insert, just do it the same way each time and record your results. You will find what % works for your measuring point and your setup through practice.

Arthur P

Switch to 4" feathers at 2.3 grains per each for a total of 6.9 grains and see what your FOC does.

Even the big 5 3/4" Magnum feathers are only 4.2 grains per each.

I don't agree or disagree with taking broadhead length into account. I understand the principle behind it but it really doesn't mean that much, IMO.