foc conquers all ask Dr.Ashby he shot a white rhino with a 40lb longbow. i would much rather prefer high foc than gpi because of tuning and the ease of tuning a high foc arrow


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foc conquers all ask Dr.Ashby he shot a white rhino with a 40lb longbow. i would much rather prefer high foc than gpi because of tuning and the ease of tuning a high foc arrow


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I don't buy that. Ashby talks a lot about FOC but I don't recall it being the end all. From 40 years of bow hunting IMO arrow weight is the most important factor. I'll tell you why. Because it lets the bow transfer more of it's energy TO the arrow. FOC doesn't add more energy to the arrow.....it helps deliver the package once it has obtained that energy. Arrow weight literally increases the bows output by adding more energy to the arrow.

I have shot 400 grain very high FOC arrows and can promise a 500 grain low FOC arrow will out penetrate the light higher FOC. Granted that is 100 grains of arrow weight and the OP's example is only 35 grains so the higher FOC at that point "might" do better........but if you are talking large gains in weight compared to FOC it's a win for arrow weight. Remember Ashby wasn't using 400 grain arrows in his tests either.......that makes a difference because he was getting that extra energy and then looking for more.

If you shoot 400 grain arrows off a 65 pound bow the waste is huge.

 

Higher FOC is going to do two things for you. One is what is mentioned already, better penetration. The other is faster arrow stabilization and cleaner flight. Now, this is all subjective and you definitely have to think through what you're doing when you're building a given arrow. Too much FOC can be more detrimental than too little.

I personally don't like ultra high FOC arrows. I also don't like super heavy arrows either. I try to find a nice middle ground between good arrow speeds and excellent penetration. This usually means, for my setup anyway, something in the 425 to 450gr range with 14-15% FOC. Seems to have done the trick on the last 20 or so animals i've killed.

 

As stated above. Ashby did extensive testing on arrow penetration and compiled a list of 12 factors that influence it. He placed the factors in order of priority so a factor higher on the list should not be sacrificed for the benefit on one that is lower on the list.

On his list, high FOC is #3 and total arrow weight is #6 meaning that FOC should not be sacrificed in order to get a heavier total weight.

His findings show that broadhead design (#4) and shaft diameter (#5) actually end up being more important than total arrow weight

 

Either will work. How important is trajectory to you?
What are you hunting?

I buried a 430gn arrow with a wasp jackknife to the fletching into a deers chest this year.
60# slow 28.5” bow.
160gns in the front 100gn head 12gn insert 50gn brass screw in weight.
This topic is over thought and discussed.

Don’t hit heavy bone and shoot the correct broadhead and don’t worry about it.

I would never go to the field with less than great stuff.
It’s not a new bow and it’s not micro diameter arrows.
Just hunt and make good shots.

If your arrow In my opinion drops more than 6” from 20-30yds your arrow is to heavy.


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Don’t hit heavy bone and shoot the correct broadhead and don’t worry about it.

Much easier said than done. The reason you shoot a heavy arrow with as much FOC as you can is because you can't predict EXACTLY where your arrow will hit. An inch or two up/down or left/right can be the difference between a pass through or a shoulder blade. I personally prefer to give myself some added protection against unforeseen circumstances.

I've hunted too long to think every shot I take will hit exactly where I want it too. If it did...I would never lose a deer.

 

I believe there is a Youtube video of a guy who does 0% FOC and slowly works his way up in FOC to like 20%. same total weight, same BH. Melted lead and put it in his arrow at different arrows to achieve this. I don't think he saw much difference at all. He did all types of testing for accuracy and penetration. One thing i think people need to consider with FOC and Dr. Ashby is he did his with a recurve or LB, not a compound. ( i am preparing for all the hate that will be heading my way) I do enjoy a higher FOC on my arrow builds around 14-17% but overall i look for a complete arrow that is heavy with thicker walls. I am no scientist but like scientist i am skeptical on everything until i try it for myself. could very well be wrong but that Youtube Video i saw is the best one to compare FOC.

 

no you are correct. dr ashby did a great job of showing the archery world what a low energy set up can do.
even using is 12 factors to build an arrow for high energy set ups work great. but for high energy set ups we do not need the foc for penetration. we need it to make sure our arrow stabilizes in flight. this may be 12% for one guy and 18% for the next. this is why we tune. most people dont realize that tuning involves adjusting foc. why do you think gold tip has the fact system. it is not to increase foc. it is to tune the set up for good flight.

now I dont know what video you are talking about. but if he is not shooting a low energy setup. the he will not see a difference in foc gain. this is a big problem because most people, no, almost all people do not realize that. anytime you see a test on foc and they are shooting a compound bow and claim, see ashby is wrong. i just proved it. have zero clue of what is going on.

 

The benefits of high FOC comes into play when your arrow comes into contact with a solid medium, especially at an angle.
Example: quartering shot and the arrow hits rib bone.

 

One thing I like about the Ashby 12 factors is that they are prioritized. The higher rated factors should not be sacrificed for the lower rated factors. And the higher rated factors often contribute to the lower ones.

For example, you can get to really high FOC by taking and ultra light arrow and loading up the point. But Factor #1 is structural integrity. So no dinky arrows!

Then, as you guys have stated, you can build the highest FOC, heaviest arrow you want. But if your arrow is flying sideways, no way you are getting penetration. However, Factor #2 is perfect arrow flight. So that should be covered as well.

The list was useful for me when I was learning to build my first arrows because it helped me know what factors I should not skimp on for the benefit of other factors.

@enewman I have been following your posts on the Facebook Heavy Arrow Hunt Club. You are definitely much more well versed in this stuff than I am. I would be very interested in see your revised list for compound bows

 

One thing I like about the Ashby 12 factors is that they are prioritized. The higher rated factors should not be sacrificed for the lower rated factors. And the higher rated factors often contribute to the lower ones.

For example, you can get to really high FOC by taking and ultra light arrow and loading up the point. But Factor #1 is structural integrity. So no dinky arrows!

Then, as you guys have stated, you can build the highest FOC, heaviest arrow you want. But if your arrow is flying sideways, no way you are getting penetration. However, Factor #2 is perfect arrow flight. So that should be covered as well.

The list was useful for me when I was learning to build my first arrows because it helped me know what factors I should not skimp on for the benefit of other factors.

@enewman I have been following your posts on the Facebook Heavy Arrow Hunt Club. You are definitely much more well versed in this stuff than I am. I would be very interested in see your revised list for compound bows

I haven’t decided if I want to put it out there yet. But I do agree with all of what you just wrote. If people would build to the 12 factors we would not be having or seeing issues like we do. Now I don’t follow all of them. But I do follow part of them.

 

Great info !
Arrows are always a favorite topic & hobby. i enjoy learning new info
or ideas.

Question,
would you rather, your arrow, flying to the target ...
be pushed to the target ?
or be pulled to the target ?

 

Great info !
Arrows are always a favorite topic & hobby. i enjoy learning new info
or ideas.

Question,
would you rather, your arrow, flying to the target ...
be pushed to the target ?
or be pulled to the target ?

only time an arrow is being pushed is when still on the string. arrow is never being pulled.

 

it does have propulsion, that's why it moves forward.
without steering.
if it is heavy at the back end, it wants to turn on its self.
- momentum -
that is why some foc is important.
with some foc, & good center shot. there is nothing for
the back end to do. no correction , the vanes just keep it
going the way its going.
an arrow pulled - foc - an stabilized - vanes - flies better in
all situations .

 

it does have propulsion, that's why it moves forward.
without steering.
if it is heavy at the back end, it wants to turn on its self.
- momentum -
that is why some foc is important.
with some foc, & good center shot. there is nothing for
the back end to do. no correction , the vanes just keep it
going the way its going.
an arrow pulled - foc - an stabilized - vanes - flies better in
all situations .

ok

 

Okay, I now know what to fund when I win the lottery...

 

hahaha i have lots of things you can fund. so hurry and win

 

I know two ways to achieve higher penetration is to increase your overal arrow weight and also increase your FOC.

Now assuming the same broadhead is used, does one of those factors (FOC or weight) have more of an impact than the other?

Let’s use these arrow builds as a comparison:

Easton Axis 340 (9.5gpi) 27” - 448gr total

Easton HEXX 400 (7.2 gpi) 27” with 50gr insert - 413gr total

Now I know some people will just say “add a 50gr insert into the axis and get high FOC and weight” - that I understand, but if someone still would like to maintain speed they may not want to jump up to a 480gr arrow (ie short draw length 26.5” low poundage 60lb)

What’s your thought

Why not go with a Axis 400 spine with a 50 grain insert and have Good FOC and 420 grains.....The Axis 400 spine in my signature are 27.5"...from the valley of the nock to the end of the shaft...about 27 1/8" carbon to carbon...422 grains on my scale.

 

Are you using a 100 or 125gr broadhead?
How do you find they fly?

 

an overall heavier arrow develops better momentum and it is that momentum, that drives an arrow during penetration. you can have a high FOC arrow and because the back of the arrow has little weight in comparison to the front, the arrow will shed it's inertia quickly when it meets resistance, because there is little weight behind the point to drive the arrow through the resistance. when considering FOC, think,..."consistent trajectory and grouping from an easily steered arrow", which is important, too, but as far as penetration,...momentum is king and that comes from overall weight.

 

an overall heavier arrow develops better momentum and it is that momentum, that drives an arrow during penetration. you can have a high FOC arrow and because the back of the arrow has little weight in comparison to the front, the arrow will shed it's inertia quickly when it meets resistance, because there is little weight behind the point to drive the arrow through the resistance.

I don’t think it works that way. Mass in motion has inertia. It’s not going to just quickly shed.

 

Arrows with same exact weight have same exact momentum when both arrows have same velocity. Basic physics. FOC is a bit more complex physics. When the higher FOC arrow hits it's medium it oscillates less, in turn losing less energy at impact. Ultimately resulting in better penetration.

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Arrows with same exact weight have same exact momentum when both arrows have same velocity. Basic physics. FOC is a bit more complex physics. When the higher FOC arrow hits it's medium it oscillates less, in turn losing less energy at impact. Ultimately resulting in better penetration.

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hit wrong button.