I just check out my F.O.C. ratings for my arrows, and I was getting 7.9 percent. I have heard that 11-12 percent is ideal. What will this do arrow flight wise?

Here' s a sight that gives a little info.
http://www.fortunecity.com/millenium/plumpton/18/archery.html

Typical FOC ranges as taken from Easton' s Tuning Guide
FITA(olympic style) 11-16%
3-D 6-12%
Field Archery 10-15%
Hunting 10-15%


I would guess flatter trajectory is why the 3d guys use it. A low FOC will affect spine on the weak side as well. For hunting you' ll want it heavier though for better penetration

Buck Magnet, I' ve found FOC with field points isn' t as critical as with broadheads. I have decent groups with 100 or 65 gr points, on the same arrows. If FOC gets too low with broadheads, my groups are not to my satisfaction. I think I' ve had as little as 6% with field points, but less than 10% with broadheads didn' t do well. I don' t shoot beyond 45 yds, usually.

BM,
Here' s a little something I found that should help.......it backs up Phil' s response nicely with an explanation that , thankfully I can cut and paste here rather than try to type it based upon my own experiences. It shows nicely what I want to say.
This info I' m gonna post I would say mainly applies to fixed blade broaheads.......mechanicals on the other hand with their aerodynamic flight characteristics, (as long as you have your bow tuned properly, with spin tested and tuned arrows) will allow you to get away with very similar FOC levels to field points.... Even tho according to the article you are still on the low side for field points, if you ARE shooting mechanicals and they are grouping good for you out of a well tuned bow then don' t sweat it. I think you might notice a difference in long range FITA type accuracy, but for practical hunting distances I doub' t you' ll see any ill effects.

(Article copied from Petersons Bowhunting Mag)
What is FOC?
If there' s one variable of broadhead flight that' s often overlooked, it' s the arrow' s front-of-center balance point, or FOC. In practical terms, FOC determines how much leverage the fletching has to correct the arrow' s flight. The farther forward the balance point is from the center of the arrow--the FOC point--the longer the lever the fletching has to work with and the easier its job. The general recommendation for FOC is 12 to 15 percent for broadhead-tipped arrows. This compares to a recommendation of eight to 11 percent for field points (for pure target applications). The difference in suggested FOC is due, in part, to the longer length of a broadhead. It' s also due, in part, to field points not having the ability to steer an arrow like a broadhead can.

Finger shooters, and those shooting shafts less than 26 inches in length, should probably look for a higher FOC. This is because shorter arrows are inherently less stable, and finger shooters, once again, need a little extra help to correct the normal arrow wobble upon release.

Note that it' s possible to shoot very accurate groups with field points with less than eight percent FOC, but again, field points are more forgiving than broadheads. Just as with fletch size, it' s better to err on the large side with FOC. You don' t want to go overboard, though (past 18 percent). Too much FOC makes your arrows point-heavy and less aerodynamic downrange.

How do you figure out your arrow' s FOC? The Easton computer program that I mentioned earlier in the article has a calculator that will do the job for you. If you don' t have the program, you have to do the math yourself. Here' s how I do it, and since I' m no math wizard, it' s pretty simple. The formula is: [(ABP ÷ TAL) - .50] x100 = FOC%

ABP is the distance to the arrow' s balance point from the nock of the arrow, and TAL is the total arrow length. (This formula is different than the one recommended by the AMO. It provides the same answer, but I' ve found it a little easier to use.) All you need is a tape measure and something to balance an arrow on (like a pencil) to use the formula. First, balance the arrow and mark the balance point with the pencil. Then measure from the throat of the nock (where the string fits inside the nock) to the mark you made at the balance point. This is the arrow' s balance point (ABP).

Next, measure the length of your arrow from the throat of the nock to where the insert goes into the shaft. This is the total arrow length (TAL). (If you use carbon shafts with outserts, measure to where the point screws in.) Finally, input the figures into the FOC formula. For example: If you had a 30-inch arrow that balanced at 19 inches, the formula would read: [(19÷30) - .50] x 100 = 13.3 percent FOC.

What do you do if your arrow' s FOC is too low? You might have to use a heavier broadhead or change shafts. Be careful here. Adding a heavier head can change arrow spine, meaning you might have to use a different arrow or, at the very least, re-tune the bow.

If you really don' t want to change shafts or components and you' re shooting vanes, try switching to feathers. They' re typically much lighter and could move your FOC forward by two percent or more. You can also try using a lighter nock.

I ran into the same problem with my current arrows. They say a solocam like a stiffer arrow, so I buy stiffer arrows.
I want to shoot carbons for durability reasons. The way to go stiffer with carbons is to shoot the hevier shafts - 65/80' s for me.
Now I end up with arrows that carry too much weight along the shaft to where a 100 grain provides minimal foc and 125 grain weakens the spine???
So, if I shoot mechanicals everthings OK. If I shoot fixed blades I' ve got to do some compromising??(move arrow rest so field points don' t shoot the same as blades). I got complete pass throughs with both styles last year. But ended up shooting mechanicals towards the end because I felt better about knowing my arrows were flying true and I could switch back and forth between hunting and target practicing.
So now I have a new bow and am worried about making the same mistake. I know I should go with the Beman 340' s for spine reasons, but will I suffer from the same low FOC issues? If I go 400' s the foc will be great with 100 gr. heads, but I fear they will be to weak for the infinity cam.

I think if the arrow flight becomes an issue with fixed blades this year I' ll just buy some " slicktricks" and give them a try- there supposed to fly just like field points.

What' s the solution? Am I missing something here?

Dave

What are you shooting on the nock end of your arrow? Vanes or feathers?
I shoot a 29" Beman ICS 340 with 100gn tip and 3 four inch feathers and my FOC is right where I want it to be and my broadhead flight is great. The key to getting good broadhead flight is figuring out where to put more weight on the arrow (the front or back)

Vanes. Feathers are more accurate, but not near as durable and rain proof. JMHO

Any body else out there shooting 340' s with plastic fletch and have a decent FOC with a 100 grain point?
Is this doable, or do you have to go 400' s to use a 100 grain point and get a decent foc?- will that arrow shoot from a 65-70# hard cam?

I' m shooting 340' s with 3 7/8" vanes and 100 grain points. The shaft is 27" due to my overdraw. I' ve never bothered to check my FOC becuase I don' t believe in it too much. My bow paper tuned well, and from there I zeroed everything else in. I don' t have any erratic arrow flight and they stack right in there. Although, using the MZE may be helping...

NYH, are they grouping well with fixed broadheads, are do you use mechanicals?