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Help with spine selection

502 Views 17 Replies 11 Participants Last post by  ThisIsMyHandle
Im planning to use a lightweight arrow for 3d this year. Decided on the Easton sonic 6mm. I’m unsure if I should use 300 or 340. My specs are 80lb and 27” draw length. Arrow length will be 25”. I’d like to be as light as possible. Im going to use 50 grain brass inserts instead of the aluminum. I feel like with the arrow length being so short, I can get away with the 340s and not be underspined. Am I wrong?
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Im planning to use a lightweight arrow for 3d this year. Decided on the Easton sonic 6mm. I’m unsure if I should use 300 or 340. My specs are 80lb and 27” draw length. Arrow length will be 25”. I’d like to be as light as possible. Im going to use 50 grain brass inserts instead of the aluminum. I feel like with the arrow length being so short, I can get away with the 340s and not be underspined. Am I wrong?
I see you said 50gr inserts but what weight points?
 

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You want it as light as possible but you are using the brass inserts instead of aluminum? What is your reasoning?

You are definitely in 300 spine territory with that draw weight/length.
 

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Your short draw length definitely helps stiffen the arrow up, but I still dont think 340 is adequate with 80lbs of draw weight.

The difference from a 340 to a 300 is 1 GPI. You're talking about 25 gn weight gain at your arrow length.

You would maybe pick up 5 fps. Thats not enough to justify going with a marginally weak arrow.

You'll see more benefit using the right spine and your arrow speed being ever so slightly slower.

Good luck
 

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Discussion Starter · #9 ·
Your short draw length definitely helps stiffen the arrow up, but I still dont think 340 is adequate with 80lbs of draw weight.

The difference from a 340 to a 300 is 1 GPI. You're talking about 25 gn weight gain at your arrow length.

You would maybe pick up 5 fps. Thats not enough to justify going with a marginally weak arrow.

You'll see more benefit using the right spine and your arrow speed being ever so slightly slower.

Good luck
thank you sir
 

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25 inches is x bow bolt territory, I bet the 340 would shoot. Find someone with a 340 spine arrow of any kind you can cut down, if you are in a club should be easy to find an arrow someone threw out with a bent insert and cut it down.

Lancaster does sell singles if you were really wanting to check but may not be worth the cost?

Arrows anre measured for spine at 28 inches, 3 inches under that changes things.
 

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Im planning to use a lightweight arrow for 3d this year. Decided on the Easton sonic 6mm. I’m unsure if I should use 300 or 340. My specs are 80lb and 27” draw length. Arrow length will be 25”. I’d like to be as light as possible. Im going to use 50 grain brass inserts instead of the aluminum. I feel like with the arrow length being so short, I can get away with the 340s and not be underspined. Am I wrong?
Use this calculator before your arrow build:

Target & Hunting Arrow Selector - Easton Archery

I like to lean toward the stiffer option usually.
 

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100 grain
So with 150 up front you want 300 spine. If you had 100 up front 340 spine would be ok. 100 grains plus standard inserts of 12ish grains and 340 would probably still be fine. I think you are overthinking the FOC though; in my opinion any arrow with at least 80 grains up front is just fine. I shoot gold tip pierces for field and 3d with 100 grain glue ins and those things are absolute lasers all the way out to 150 yards which is where my sight maxes out. I think 340s with 100 up front would be just fine for you at any range. Just my 2 cents.
 

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Go literally as stiff as you can. You'll want a stiff arrow with that setup.

This has been said a million times, but you can't be too stiff as long as you know how to tune your bow. I always go as stiff as possible, accounting for GPI of course.
 

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300, you could get 250s to tune as well. No way I would go with 340.
 
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You could check out the Victory RIP XV arrows if you really want light weight.
Or Gold Tip Quantum/Airstrikes. You can get a super light 250 spine and really load up the front without getting stupid heavy total arrow weight.

I'm building some RIP XVs in 300 spine with a 70 grain stainless half-in (half-out) and a 100 grain head that will come in at just under 400 grains.
 
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