What happens if your arrow is over-spined?

rob86jeep

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I've heard that if you're over-spined it WILL affect your arrow flight, it only makes your bow less forgiving, and it won't matter on a properly tuned compound bow. So, what is the actual answer (as it can't be all 3)?

I recently got a new bow (70 lbs with 28" draw) and decided on Easton Axis 260 spine arrows with 200 grains up front (125 broad head and 50 brass insert). There was one guy at the archery shop who looked at me crazy saying there's no way he'll be able to tune that and another guy (younger) so said it was fine and he would actually recommend that spine and there was no issue with that much weight up front. Just curious if this is an old vs new mentality or something else altogether.
 
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In my experience the spine charts are a starting point and not hard and fast. The best thing you can do is take a couple different arrow configurations and tune them to see what flies the best with your rig. You should be able to get those to fly where you want with good form and tune.

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I shot the 260 HEXX for a long time with 200 up front and now have the 280 4mm Injexions with 235 up front. The shop owner I deal always shakes his head but we’ve never had any issues with tuning. I wouldn’t worry about your set up one bit.
 
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Your setup adds up to 175 in my head.

Not going to see much adverse effect with a compound from a stiff spine. Look at the spine on a bunch of the indoor saw logs they use. Stiffer spine is going to be less forgiving, but will tune a broadhead easier.

I have been running a 250 spine with 14 grain insert and 125 grain head on a bow @72# and 29" draw. Arrow is cut somewhere around 28". Really happy with how it tunes.
 
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rob86jeep

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Your setup adds up to 175 in my head.

Not going to see much adverse effect with a compound from a stiff spine. Look at the spine on a bunch of the indoor saw logs they use. Stiffer spine is going to be less forgiving, but will tune a broadhead easier.

I have been running a 250 spine with 14 grain insert and 125 grain head on a bow @72# and 29" draw. Arrow is cut somewhere around 28". Really happy with how it tunes.
You're right, 175 up front. I was originally planning on a 125 broad head and 75 insert but dropped down o a 50 insert when I tallied up my total arrow weight vs speed. I still want to shoot pretty far out (80 yards or so) without a huge pin gap so 530 total arrow weight is where I decided to start. I'll drop down or go up a little after I start pushing my distance out a little.
 

eltaco

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I’m this case, the younger fellow is giving you sound advice. Optimal spine is absolutely best, but I don’t expect you’ll have an issue with too stiff a spine on this setup. You’re running a lot of point weight, to boot.

I would absolutely rather shoot too stiff a spine, than too weak.
 

Marble

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Spine charts are a guide. They get you in the ballpark you need to be. Soon as you add extra point weight then the spine starts changing. Someone here will run your numbers. They will need some more numbers, but I would guess
It's close.

And stiffer is better... ask my wife.
 

Brendan

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The theory is this:

Build 3 different sets of arrows. One weak, one optimal, one stiff. Tune them all such that bare shafts and broadheads fly perfect with field points. Then, shoot groups with them at long range. Each at a fresh target, mark and discard your true flyers. Do it over enough of a sample size, the "optimal" arrow will give you the smallest group and the most forgiving setup.

Dudley from Nock On had a bunch of articles on it that he coined the "HIL Method" or Horizontal Impact Line method. Practically though, I don't think most people can shoot well enough to tell a difference after you get everything tuned and flying perfect.

I have never subscribed to the theory of setting a bow up, and then cutting length or adding weight to get it to tune. I use a program and personal experience to estimate spine requirements, build the arrow I want, and then yoke tune, shim cams, etc. until the bow tunes. Never had an issue with too stiff except one arrow build that was WAY WAY WAY too stiff. Couldn't get it to bare shaft tune, but broadheads still shot fine.
 

5MilesBack

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Here's something I ran into recently. First of all, I'm shooting a PSE Freak SP at 75lbs and just under 33" draw with 30" arrows. Bare shaft tuning at 20 yards had the BS nock right and impacting just left of fletched........verified 1/2 dozen times with multiple grips. So I tried my 125gr Shuttle T BH at 60 yards against field points. BH's consistently 5-6" right of FP's. That's the opposite reaction that the bare shaft is showing, so which do you tune to??? This was with .200 spine GT Kinetic XT's.

So I tried it with my .250 spine BE Spartans and had similar results as with the Kinetics for both BS's and BH's. So then I tried my .300 spine Easton ACC's and BH's and FP's are almost touching, while the BS's are still about 2" nock right at 20. I verified those BH's 1/2 dozen times with similar results each time.

So, I'm going to clean up the bare shafts first and then go back to 60 yard BH's as soon as my new 125gr Exodus with swept blades get here. But really odd that the lightest spine BH tunes the best out of this setup right now, as 300's should be under-spined.

And BTW, I had it all setup well with the Kinetics and had BS's and BH's perfect but I didn't like the way the bow felt, so I changed that all up to get a better feel and here I am. It will tune though AND give me a better feeling bow at the same time.......eventually.
 

Trial153

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I have never found the set ups that I tuned with overly stiff arrows to be especially forgiving. Just because I can tune bow/arrow combination doesn't mean that its optional.
 
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Bottom line is being over-spined is MUCH better than being under-spined.

If you can tune a bow with any degree of success then you shouldn’t have an issue going with an arrow that is on the stiff side. IME the ones that aren’t knowledgeable enough of the tuning process typically stay away from the heavier/stiffer arrows for that reason.
 

stonewall

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Tim gillingham in a YouTube vid said something along the lines of there’s not too stiff provided power stroke of string runs right down center of the arrow

in my personal experience. A few years ago, My daughter was shooting 500s and had arrows all over the target face at 20. Guy at shop gave her some 600s and the groups tightened significantly
 

Beendare

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I've shot over spined hunting arrows for many years.

Optimal? All I know is back when I was younger with better eyesight and could shoot well, I could hold sub 3" groups at 50 yds with my fixed BH's on an overspined arrow- shot over spined for decades. Tunes easy with none of the issues of being underspined.

____
 

SlickStickSlinger

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in my personal experience. A few years ago, My daughter was shooting 500s and had arrows all over the target face at 20. Guy at shop gave her some 600s and the groups tightened significantly

Can you elaborate any further?

I wonder if he handed her the lesser spined arrow because it was less weight to flick at the target.
Do you remember the draw weight?
 

Beendare

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Where my recurve has a tight range on arrow spine that works..... a modern compound with a shoot through window is a whole different animal.
We don’t need Archers Paradox to get around the riser of an old 80s compound, kids bow, or recurve.

Now, what we are talking about with modern compounds is Arrow oscillations. By now we all know that with BH’s the trouble comes when you are under spined.

personally I think the arrow charts of today are still back in the 70s. they are designed to give you the lightest arrow that will work for your bow.

These pros aren’t much help. In my experience they all shoot a fairly light arrow to retain their long range trajectory.

fwiw, i’ve been able to BH tune five bows in the last 20 years in about a half an hour each shooting over spine arrows.

With a guy have problems tuning a stainless steel rod with zero flex? I couldn’t tell you but I can tell you that one or two spine size is over is no problem.
 
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Apapro

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Rob86Jeep you'll be fine with your setup your definitely spited stiff enough. Im running .250 spine arrows with 45 brass insert and 100 gr iron will up front....out of 80# bow at 30" draw. They shoot excellent so you'll have no issues. Ive also tried and shot the 75 brass inserts up front also (again tuned very well)

465 gr killin stix original at 324 fps.
 
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