I would definitely go to a lighter shaft if you’re wanting to increase FOC. 1″ shorter feather will not make much of a difference.

A significantly lighter shaft will give you a big boost in FOC. As the FOC gets progressively higher the more gain you can make (in FOC) by reducing the fletching size – and the longer rear leaver (the fletching’s ‘stearing arm’) your arrows will have at the higher FOC will let those smaller feathers exert substantually more pressure than they would at lower FOC.

Ed

M wrote: So then I should buy some arrows with the lightest GPI and try to tune the bow to the arrow?

Yes lightest you can find but a size TOO stiff for your bow weight so that you can load up the front. Loading the front will weaken back to straight.

Richie

M wrote: So then I should buy some arrows with the lightest GPI and try to tune the bow to the arrow?

Yep. What we’re all saying, in different ways, is use the lightest GPI arrow spined correctly for the broadheads you are using. Spine charts are generally not going to show the proper spine arrow for use with a 300 grain tip. Unless stated otherwise, usually they will assume the use of a 125 grains tip.

If you want your FOC as high as you can get it, buy the stiffest shaft you can in a lightweight carbon. Keep the shaft as long as possible. There is no reason a shaft has to be cut except to make it stiffer to match a heavy tip weight (assuming you’re not changing your strike plate to something thinner).

Simply load up the tip weight until it matches the dynamic spine of your setup.

Str8arrow wrote: If you want your FOC as high as you can get it, buy the stiffest shaft you can in a lightweight carbon. Keep the shaft as long as possible. There is no reason a shaft has to be cut except to make it stiffer to match a heavy tip weight (assuming you’re not changing your strike plate to something thinner).

Simply load up the tip weight until it matches the dynamic spine of your setup.

I humbly disagree. The shorter the shaft, the lighter the spine required for any given tip weight. The lighter the spine, the lighter the arrow, the more FOC weight you’ll have.

Let me take Gold Tip arrows as an example. A 5575 weighs 8.2 gr per inch and is a .400 spine. A 7595 weights 8.9 gr per inch and is a .340 spine. A 30 inch 5575 arrow is only 21 grains lighter than a 7595 arrow of the same length. Yet a 7595 will probably allow me to put at least an extra 100 grains on the tip and end up with the same dynamic spine as the 5575 with a 100 gr less on the tip. In fact, if memory serves me correctly, it’s probably closer to 200 grains. Also, weight on the tip affects FOC far greater than weight distributed along the full length of the shaft. There is relatively little difference in shaft weight on weak spined carbon arrows, vs stiff spined carbon arrow of the same model.

In other words, a 30″ 5575 with the correct tip weight to be shot of of a given bow, will have a lower FOC than a 30″ 7595 with proper tip weight, shot out of the same bow. I hope I said that so it makes sense.

I’m just saying that the heaviest spined arrow may be over-spined arrow with even the heaviest tips. My set-up is a perfect example of that.

Patrick wrote: I’m just saying that the heaviest spined arrow may be over-spined arrow with even the heaviest tips. My set-up is a perfect example of that.

My solution to that has been to keep it as long as possible and add as much weight as needed. Of course, there is a limit to weight that you can add, but I haven’t found that to be a problem. The biggest issue has been finding a carbon shaft that is stiff enough to handle a real heavy tip weight (500-600 gr). I’d like to make a 35-40% FOC arrow, but it requires an incredibly stiff shaft that is still lightweight. At this point, it’s not an off-the-shelf arrow that will achieve that.

Well … taking this back to M’s original proclamation: “Experimenting with FOC is expensive!” Well, yes, but relative to what? In my humble life the fastest way to throw money away and damage my health all at once is, say, a Valentine’s dinner out … $120 easily in this tourist town, with drinks and tip. I can do a LOT of arrow experimenting with that, and live longer too! :lol::wink:8)

“It’s only money.”

I have been building arrows of late for my 71ish lb. recurve. I have been using GT Big Game 100’s and have gotten the FOC to 31% but it had to be in the 1000 grain range to do so. And that is not all bad. I like heavy for several reasons.
As I have mentioned before I have used the GT Ultralight 400 and 500 and built arrows for my sons’ lighter weight bows with FOC 32.7% and 820ish grains.

I just got some Ultralight 300’s to try with my 71 lb. bow. I just put everything together and shot it. It is 31.2% Ultra EFOC and only 789 grains. I have only cut off 1/2 inch of the 32 inch arrow. I still have room to cut and make it stiffer if I want to add 50 more grains. Then it would be around 32.2%.

I totally understand this is not nearly as important as loosing our Country and our liberty, literally as we speak, but it is just a little tinkering success.

Richie

M,
I suggest the GT Ultralight Entrada 400. It is .400 spine and 7.4 gr./in. Probably keep it full length. You could probably make the 500’s work as well by cutting shorter, etc.

You can get them at eaglearchery.com for $3.99 each and can get 6 at a time.

Richie

[quote=M]If I buy arrows instead of the valentines day dinner I won’t live long.

TOUCHE! 😆

David Petersen wrote: “It’s only money.”

:lol::lol::lol: I like that, in reality what is money anyway, its just paper anymore, we have no gold standard, lol. But I have learned that it can be quite inexpensive. I just bought brass inserts for my Beeman ICS bowhunters and dramatically increased my FOC. But I imagine it wouldnt be so easy with wooden shafts?

Patrick wrote: Yep. What we’re all saying, in different ways, is use the lightest GPI arrow spined correctly for the broadheads you are using. Spine charts are generally not going to show the proper spine arrow for use with a 300 grain tip. Unless stated otherwise, usually they will assume the use of a 125 grains tip.

someone should get on that!! Would be nice to have a chart to correspond to different tip weights!

I shoot Beeman ICS bowhunter shafts 400’s, 8.4 gpi. I would say that if you go to 9 gpi you will be perfect, my shafts are still a bit light, for my bow. I am around 8.98 gpp, and the lowest that I feel I should be going is 9 gpp.

What you are using now is fine, don’t spend what you don’t have.
Your current set up is PLENTY.
I shoot similar set up 700g arrows off my 53# bamboo longbow that I draw to 27″ {CX 150’s though} and it will shoot through my shed.

M, you need to see what the bare shafts do, in comparison to your fletched shafts. With that much fletching area ANY EFOC arrow is going to be flying straign before it hits the target, even if the dynamic spine is WAY, WAY OFF.

Ed

From my last post:

“I just got some Ultralight 300’s to try with my 71 lb. bow. I just put everything together and shot it. It is 31.2% Ultra EFOC and only 789 grains. I have only cut off 1/2 inch of the 32 inch arrow. I still have room to cut and make it stiffer if I want to add 50 more grains. Then it would be around 32.2%.”

Well I now have the GT Ultralight 300 at 31 5/8″ from groove to end of insert, (then another 1/4″ to back of broadhead). 825 grains and 32.5% Ultra-EFOC shooting from a 71 lb @ 31 inch Widow recurve. Very simple loaded arrow. It just gets better and better.

CORRECTION:
829 grains and 32.3%

Richie

Sapcut wrote: Well I now have the GT Ultralight 300 at 31 5/8″ from groove to end of insert, (then another 1/4″ to back of broadhead). 825 grains and 32.5% Ultra-EFOC shooting from a 71 lb @ 31 inch Widow recurve. Very simple loaded arrow. It just gets better and better.

CORRECTION:
829 grains and 32.3%

Richie

Stick a good BH on the end and I’d shoot buffalo all day with that setup, Richie. Now go and shoot something big with it so we can see what it does! 😀

Ed

Is there some sort of correlation between the gr./in. and the affect of the spine? Or is any .300 spine arrow of the same length going to react the same regardless of the gr./in.?

I had been trying to load an Ultra-EFOC setup with the 7595 Trad blem arrow. It is supposed to be .300 spine just like the Ultralight 300 that I described in the last post. The 7595 Trad wasn’t even close. I had to cut it 1 inch shorter with 40 gr. less up front to get it too fly right with the same bow.
I am guessing that because it is a “blem” that it is not spined .300. I have asked Big Jim that sold these blems and he said he has never had a spine problem in the thousands he has sold. I think I have the first one.

The Gold Tip Ultralights are definitely the “go to” arrows if Ultra-EFOC is on your agenda but I was just curious about this issue with the 7595 Trad blems.

Any thoughts and answers are appreciated.

M,
First of all anything I type on this site is stealing information or plagerizing several people that I am priveledged to learn from. I then just try to listen, learn and put to practice.

When trying to achieve Ultra-EFOC, I now know the first step, like Dr. Ed and King DeVille has said before, is to get an arrow that accomplishes two things:
1.) Too stiff with for your bow/pull weight and 2.)lightest gr./in you can get.
The above will allow you to load up the front which will weaken your already TOO stiff shaft back to the middle.

A while back Dr. Ed mentioned using the GT Ultralights. Well I looked and looked and found the GT Ultralight Entradas at EagleArchery.com for $3.99 each plus $6 handling and can be bought in 1/2 dozen at a time. It is shafts only. Fletched shafts may be available as well but not sure. BTW…my Ultra-EFOC setup mentioned above is with three 4″ hand cut banana feathers.

Another thing about getting high FOC is efficiently managing the weight up front. For example, the first GT Ultralight 300 I loaded was 826 grains with 31.2% FOC. I then used another arrow and cut it only 1/16″ shorter, moved the weight around getting it more and more to the front of the arrow away from the fulcrum.
It is now only 3 grains heavier and 32.3% Ultra-EFOC. Big difference by just managing the weight more efficiently.

They fly great and I will be shooting 3D tournaments with these arrows.

Richie

Richie, you’ll virtually always find a difference in the dynamic spine when going from a lower GPI shaft to a higher GPI shaft (even when they are of the same brand). Here’s why. The inside diameters (ID) are generally the same (so the same diameter inserts will fit). The shaft’s extra GPI are generally gained by use of either a larger outside diameter (OD) or use of a somewhat different material and/or construction technique.

To change the GPI manufacturers have add weight somehow. That changing the material or construction technique would influence the dynamic spine is obvious, but the other type changes are more complex.

A larger shaft OD means it effectively reduces the degree of center shot of your bow. When “all else is equal” that means you’ll need a weaker dynamic spine (or more tip weight) to tune properly. Offsetting that is the fact that the higher GPI shaft has greater shaft mass towards the arrow’s rear. This means more ‘push’ from the rear due to the shaft’s mass, which results in greater shaft paradox, and slower recovery from paradox. The greater paradox resulting from more weight at the shaft’s rear then requires a stiffer dynamic spine or reduced tip weight to tune at the same shaft length. When the ‘new shaft’ is both larger in OD and has a greater GPI it becomes a balancing act to counteract the opposing forces affecting the dynamic spine caused by the difference in the net effect between these shaft dimensions.

The explanations can become even more complex. Sometimes there is a tiny difference in shaft ID too. The ID between the lower and higher GPI shafts will still be close enough that the same inserts can be used, but they won’t measure exactly the same ID. Use of a Varner caliper will tell you what’s been changed.

Static spine is merely a rough guideline. Every specific shaft is going to tune slightly different. It’s precisely like handloading a rifle cartridge; changing any parameter; even just the primer or brand of case; changes everything about how the load performs.

Hope that explains your question,

Ed

Then that explains what I experienced with the 7595 Trad blems versus the Ultralight 300. Both being .300 spine but different wall thickness.

More great info. Thanks

Dr. Ed Ashby wrote: M, you need to see what the bare shafts do, in comparison to your fletched shafts. With that much fletching area ANY EFOC arrow is going to be flying straign before it hits the target, even if the dynamic spine is WAY, WAY OFF.

Ed

Exactly!!!!! The glue surface not only stiffens the shaft, the aerodynamic stabilization (large feathers) does too! That is why you shoot the shaft bare to tune first. Tape up the back of the arrow the lenghth of the fletching with electricians tape.Cut to length with good flight, fletch it up, Bingo! Eliminate the tuning weak to compensate pipedream, which is sometimes an endeavor into the twilight zone. These arrows must be tuned to each Bow. Will more than likely not be exact dynamics in other Bows similar.

[quote=”Hiram Tape up the back of the arrow the lenghth of the fletching with electricians tape.Cut to length with good flight, fletch it up, Bingo! Eliminate the tuning weak to compensate pipedream, which is sometimes an endeavor into the twilight zone. These arrows must be tuned to each Bow. Will more than likely not be exact dynamics in other Bows similar.

Hiram

I do not understand about the electricians tape. Do you wind it around the arrow to simulate the wt of the fletching? And how do you know how much tape?

Tom

Hey Tom,just use electricians(BLACK)tape. Spiral wrap like a Barber shop pole about 1/4 inch gaps the length of your fletching.:)

Please see my comments on getting efoc in wood arrows this forum. $ are hard to come by . Cheap lets you experiment for almost free.