Arrow Spine Question

[samc]

Im looking at a new arrow build and am wondering what spine stiffness I should run. Here are my specs:
Arrows: Easton 5mm FMJ
Arrow length: 27"
Draw Weight: 70 pounds
75 grain brass insert
100 grain broadheads/tips

Wondering if I should run the 300's or 340's. The chart says 340 but I don't think that takes the added weight up front into account. What is everyone's take on this?

Thanks for the help!

 

[roadrunner]

300. The skinnier the shaft, the more flexible it is.

 

[Brendan]

300. The skinnier the shaft, the more flexible it is.

Not true. Spine is a standardized measurement, so a 300 spine is a 300 spine regardless of diameter.

But I do concur - 300. Depending on the bow and how much weight up front, you could even go stiffer.

 

[bguitierez]

Im looking at a new arrow build and am wondering what spine stiffness I should run. Here are my specs:
Arrows: Easton 5mm FMJ
Arrow length: 27"
Draw Weight: 70 pounds
75 grain brass insert
100 grain broadheads/tips

Wondering if I should run the 300's or 340's. The chart says 340 but I don't think that takes the added weight up front into account. What is everyone's take on this?

Thanks for the help!

I'd run a 300 spine if I were you brother.

Sent from my SM-N920R4 using Tapatalk

 

[samc]

Ok ill go with the 300's. Thanks fellas!

 

[roadrunner]

Not true. Spine is a standardized measurement, so a 300 spine is a 300 spine regardless of diameter.

You outsmarted yourself. Please reread the posted question, then think about my answer and you'll see where you went wrong...

 

[Brendan]

You outsmarted yourself. Please reread the posted question, then think about my answer and you'll see where you went wrong...

His question had nothing to do with diameter. A 4mm 300 spine, 5mm 300 spine, and a 6mm 300 spine arrow will deflect exactly the same amount when measured the same way (.3" in fact if you support it correctly and use the standardized weight). Therefore, a skinnier arrow is not necessarily more flexible, which is what you said. Not true.

If you want to get into the dynamic spine of an arrow - that's different. Referring to adding weight to the front of the arrow weakening your dynamic spine, weight to the rear of the arrow stiffening it, shortening it stiffens it, lengthening it weakens it...

If you're getting at something else, I'm not seeing it...