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Discussion Starter · #1 ·
Hi Guys and gals,

I was hoping someone with experience in TAP or similar could help me out. I'm trying to tweak my setup. I'm shooting a G-force at 29" draw with 28" arrows (Carbon Express 3-D select 300). I haven't had it on a scale, but I have 70 lb limbs and they are backed out to around 62 lb or so. (about 3 turns). My arrows were 29.5" and I was shooting them with 125 and 100 grain heads. I was getting a bit of a right tail whip that I could correct by pushing my rest ~3/4" left of centershot. But, I wasn't getting any decent grouping at 10 yd (3 arrows, 3" diameter group). More troubling in my mind, was that the arrows were entering the target at different angles. To stiffen the arrows up I cut them down 1.5" and dropped my point weight to 100 grains. That helped a little. Next I dropped my point weight down to 75 grains and now they are all grouping great (touching arrows at 10 yd).

Are my arrows underspined? On all of the charts I am borderline between 200's and 300's. The 300's are stiffer so I thought they would be fine. But playing with point weight a little makes me think I am underspined.

Am I right?

Thanks,
Rick
 

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I just looked at ATA and here is what I can up with. I don't know what your IBO speed or BH is, so I ran it thru my Cougar III.

The 300s are too stiff and have an FOC of around 8. The 200s are in the middle of the green zone with an FOC of 9, but are too light. They weigh around 295g with the 75g tips, and are under IBO.

A 90g tip would bring you up to IBO, give you an 11 FOC, and still be in the center of the green zone.

Hope this helps.
 

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Discussion Starter · #3 ·
am I underspined

bowregards,

my brace height is 5 1/4" and my IBO is 319. It has the old maxis cams that have a fairly hard curve to them.

With a 100 grain head the 300's give me an FOC around 15%. I measured them already. I am shooting 2" blazers so the back end is really light for me.

The 200's are too light for my bow for sure. I started with CX200's when I switched off of 2216 xx78's. I was cracking the back end of the shafts from what I am guessing was too much shock. I had 3 or 4 do that before I bumped up to the 300 size.

Thanks,
Rick
 
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