Recommendations?

[Ptaylor]

#4641

So to say the least, the last couple of months have been eye-opening for me. I’ve been reading through all the Ashby files and forums on here and Tradgang I can about arrow performance, and you guys really frustrate me cause I thought I had it all figured out last year, but clearly don’t:shock: I’ve tuned some wood arrows in for a couple different bows, and it went smooth, really easy to tell which spine worked for each bow. However, I can’t get the FoC I was hoping for and it seems like that is a common theme for woods.

So now I’m trying to tune in some EFOC carbon arrows and having some problems. I shoot a 65# selfbow @ 29″ which is my draw length, the arrow rest is nowhere near centershot.

I’ve been testing 3 different arrow spines. They are Beman ICS Bowhunters 300, 340, & 400.

The 300 = 32 7/8″ with a 25.2% EFOC

The 340 = 31 3/4″ with a 25.9% EFOC

The 400 = 31 1/4″ with a 26% EFOC

I’m using different shaft lengths, cause its all the bow shop had in stock that I didn’t have to purchase a 1/2 dozen of them.

For points I’m using a 100 grain brass insert and a 250 grain point.

problem: All 3 arrows do the same thing. At 10-12 yards they hit the target straight on. Closer they are acting stiff, nock right. Farther they are acting weak, nock left. I’m right-handed. From 25-30 yards away I would expect to see the wrong spines start to veer off to the left or right (like I’ve seen with woods), but that doesn’t happen. From those distances they keep oscillating in the air and hit the target but are nock left.

From an earlier post, “Tuning?” I have concluded most of this is probably due to my form. But when I bareshaft tuned my woods I could easily find the spine that flies straight. My woods for this bow are spined at 75-80 lbs. 30 3/4″ valley of nock to back of point with 225 grain points.

If any of you guys with more experience have an idea of what spine carbon shafts theoretically should work, or other ideas that would be appreciated.

preston

[David Petersen]

#32563

Preston– I’m only half joking when I suggest that shooting carbon arrows from a selfbow is bad karma. 😯 The laws of the universe don’t want to see such an unnatural mismatch work. 😆

You are right that getting EFOC with woods is darn hard if not impossible. At this moment the finish is drying on another batch of Sitka spruce shafts I’m building to hunt elk with this fall, with an Osage selfbow. I shoot carbons and woods, as the mood strikes, with my Java Man deflex/reflex longbow, but woods only with any wood bow. Remember that EFOC kicks in as a primary producer of penetration only after you have the 650 minimum total weight. Weight comes first. (Back when I first discovered Ashby’s early Natal Study, prior to his writing about FOC, I shot completely through two elk with 743 grain hickory arrows having only 125-grain broadheads. What EFOC does is to let us shooting less weight and still get pass-through penetration.) With Sitka spruce, which is light for its spine weight, and 300-grain glue-on points I can approach 20% FOC with under 700 grains total, and they shoot great. I’m betting that’s plenty even if I hit bone … and sure hope to find out. 😀

[Ptaylor]

#32740

I agree, its hard emotionally/spiritually to shoot carbons from a wooden bow, but looking at the benefits of EFOC and all the other findings of Dr. Ashby, I’d like to shoot the best arrow I can.

Might have to try some lighter weight wood. I was using Ash cause I thought it was tough.

I put some really small fletching on the carbons. 2 feathers at 180 degrees, 2″ long, 3/8″ high at the back and tapering down to 1/4″ at the front. With those fletchings the arrows flew really well, maybe making up for bad releases or form. But still all 3 arrow spines flew straight from 30 yards, no veering off to the left/right.

[Troy Breeding]

#34390

Selfbows are a totally different dog in the race of tuning arrows to glass bows.

It’s not how much your sight window is off center. Heck, my glass bows are 3/16″ before center (built out that way with pads) to allow for the dynamic spine of the shafts when shot.

Another thing to remember is most wood bows just want shoot as hard as glass.

I’m only guessing since I havn’t seen your setup, but I’d almost be willing to bet your shafts are just too stiff.

Have you tried anything in the 500 spine range?

The reason I say this is how you describes the different effects of the shafts at different distance. Up close they show stiff. At mid range fine. At longer distance weak.

Most likely this is caused by banking off the sight window and giving you a false reading. Up close they havn;t had time to do anything funky. At mid range they are in mid correction. At longer distance, the banking off the sight window starts to show.

Another thing to remember is the diamemter of the shafts. Most woods with any kind of spine are 11/32″ or larger. Most carbons are 5/16″ or less. This means the center of the shafts are in different corralations to the center of the bow even if the shafts are the same spine.

Troy

[Ed Ashby]

#34517

I think Troy has you onto the right track. Sounds like the dynamic spine is too stiff with the shafts banking off the arrow plate during initial paradox..

Ed

[Ptaylor]

#34553

Thanks Troy I’ll try some lighter spined arrows.

Just so I’m understanding this correctly, theoretically an arrows spine should go down as you increase the FOC, correct?

[Ptaylor]

#35245

You were right on the $ Troy! The 500s shoot perfect, no tail wag at all, straight to the target. I’m wondering what the actual spine of this arrow is? Here are the specs:

ICS Bowhunter 500

7.3 gpi

30.5 ” bop

250 grain head

100 grain insert

It shoots nice with 29% FOC; however, only 588 grains, bare-shaft. So not as heavy as needed. I want to make sure I understand this right, so correct me if I have this wrong:

If no bone is hit, then higher FOC leads to deeper penetration. If a bone is hit, then arrow mass is the deciding factor >650 grains. So working under the assumption that you might hit a bone, its better to have a heavier arrow, then work on better FOC.

preston

[Troy Breeding]

#35669

The good Dr. would be better at explaining this in full, but if I understand it right high FOC will help offset the lack of weight. I do know that arrows of equal weight and different FOC will lend it penetration factor to the higher FOC arrow.

Adding another 62 grains to the shaft isn’t that hard. However, as you add interial weight you will decrease the FOC and most likely will have to retune. Often by adding weight the only retuning will be slightly shorting the shaft.

As far as increasing FOC requiring weaker spine? It all depends on the bow. Too often people read the results several of us have gotten and think they have to start with the highest spine possible. Every bow, every shooter is different. Heck, I even have bows of the same design and weight that require different spine shafts.

Troy

[Ptaylor]

#35673

Thanks for the info and help Troy.

[Ptaylor]

#37184

So I put some 3″ brass footings on the arrows. These were hand cut so they are between 90-97 grains, which puts these arrows +/- 685 grains bareshaft (I haven’t weighed them with fletching on). Still at 29% EFOC.

This is my first time shooting an arrow with a really high FOC, and it is AMAZING! Just like you guys say, these arrows fly straight, quiet, and hit the target hard. I’m a believer.:D I’ll put some pics up later.

[Troy Breeding]

#38908

If only the others would open their eyes and minds as well.:D

Troy

[Bruce Smithhammer]

#39041

Ptaylor wrote:

This is my first time shooting an arrow with a really high FOC, and it is AMAZING! Just like you guys say, these arrows fly straight, quiet, and hit the target hard. I’m a believer.:D

[Author]

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