Arrow F.O.C. what is ideal, and how is it measured? Anyone?

[Little Tree]

Can someone explain to me how F.O.C. is measured, and what is ideal...what is too much? too little?
Thanks, LittleTree

[Dan Worden]

For hunting you need at least 10%.  As for optimum that open for discussion.

I can't remember the formula. If no one posts it I'll dig it out tomorrow.

I made a quick, easy to use chart that is in the "how to" section/forum so you don't have to the math.

http://www.tradgang.com/upload/terry/focchart_A.pdf

[Rick McGowan]

Historically, 12% has been suggested as the ideal, with a range of 10-14% considered acceptable. I've done lots of testing over the years of arrows with foc's ranging probably from 8-18%. What I found that was the perfect foc for my hunting arrows? Surprise 12%. To measure foc; 1)measure full length of arrow in inches
2)find and mark center point of arrow
3)find balance point of arrow and mark
4)measure distance between balance point and center in inches, divide this number by the length of the arrow and multiply by 100.

[Ray Hammond]

When I shot aluminums my experience was exactly the same as Rick's... the man knows his stuff.

To complicate things a little for you, though, my experiments with carbons has changed my feelings on FOC. I load the front end of carbons up with a steel broadhead adapter, a 160 or a 190 grain head, a brass shaft insert, and sometimes weights behind the inserts, to achieve good heavy shafts. As you know, carbons are comparatively light on their own..and through the years we have been putting weed whacker line, aquarium tubing, other carbons and just about anythign else you can come up with to get them heavier, because our kind of bow does better with a heavier arrow. Some carbons with just regular field points in them in my opinion are close to a 'dry fire' on some recurves and longbows they are so light.

I am usually shooting 625 to 800 grains..and as you can see, nearly 300-375 grains can be on the tip end of the shaft. This is because I shoot 61-65 lb bows normally.

What I find is that the heavy tip and smaller column (even most of the fat shafts are smaller OD than most aluminums I could shoot) it SEEMS that the tip weight PULLS the shaft through the target..something like a locomotive engine pulls a train full of cars...and you know how long it takes a big train to stop..momentum is everything to penetration. They straighten up very quickly coming off the bow..its just a 'dot' of color from the bright nocks actually, pulling away from the bow.

One caveat however- this only works if you buy the stiffest spine available in the particular shaft you buy. If you buy the charted spine shaft you cannot load it up with weight like that under normal conditions because even cut down to your draw length they are just not stiff enough to handle that weight forward- as it really lowers the spine of the shaft to have all that weight in the tip.

Or you can just use hickory shafts with a regular head on them...and achieve great mass, great strength and durability without the excess FOC. Options, options, options.

[Hornseeker]

What do you think of the Good Dr.'s test results regarding penetration increase at 18% and above...

Really seems to make sense to me...and I cant argue against it since I have VERY little personal experience with arrow penetration on critters...

Ernie

[**DONOTDELETE**]

I think I am in the middle on this. I shoot 30" spruce arrows with 160gr heads, spined to 55-60#, shooting a 50#@28".  I receive 13.333 FOC at 170 fps. That seems to give me great flight and significant penetration. I like shooting practice and 3D shoots with the arrows I am going to hunt with. This gives me an arrow that accomplishes both.

[Kindred Mark]

I just did the math on my arrows. Like Rick I weight up a stiff carbon.  The math said 24.21% FOC.  I don't shoot much beyond 30 yards and I do notice a difference beyond 35 yards. Arrows fly great within my effective range without significant drop and I have had no problem with penetration.

Mark