Am I underspined?

[elkaholic06]

Hey guys,

I'm shooting a 70# compound bow, with a release, with an IBO speed of 322 fps. Arrows are Gold Tip Hunter XTs (.340" spine) that are cut to 28" and tipped with a 125 gr point (total arrow weight is 420 grains). Do these arrows have an appropriate spine for my bow?

Thanks much!

 

[emrah1028]

Draw length?

Emrah

 

[jvanhoy]

You should be in good shape.

 

[Elkmagnet]

You need to use their chart
https://www.goldtip.com/arrowcontent.aspx?page=chart

And move one box stiffer as directed here

https://www.goldtip.com/arrowcontent.aspx?page=recommendation

You need 300s for that combo

 

[Joe Hulburt]

I'm shooting Easton FMJ 340's out of a similar set up and cannot get broad heads and field points to group. I am fairly certain I am underspined. Trouble is they don't make FMJ's any stiffer so it's back to the drawing board...

 

[Tkaldahl2000]

According to the Easton tuning guide underspined broad heads impact to the right of the field points and overs pined will impact to the left. I am right on the border between 400 and 340. I couldn't get the 340s to broad head tune, but the 400s wouldn't paper tune. With the 400s my broad heads and field points hit in the same place. For deer I use rocket steelhead 100s, but I still wanted to make sure that all available energy was going to penetration.

 

[beginnerhunter]

Similar question... I'm using 27" shafts with 63 lb IBO 325. GT hunter XT 400 with 100 gr mechanical for deer. If I were to setup for elk, would u all recommend 340 with 125 gr fixed blades or stay with 400 and 100 gr and switch to fixed?

 

[Jwill]

http://www.pinwheelsoftware.com/default.aspx

I recently went through the exercise of getting new arrows and this tool was very helpful for arrow selection/setup. I would bet it's going to tell you to go with a heavier insert for greater foc and to go with a 300 spine arrow, but you'll need to check for yourself. I think it gives you one use for free, then you'll need to buy the software ($20 I think).