3 Rivers spine calculator

[Cavscout9753]

So I'm waiting on parts to come in the mail and have been playing with this spine calculator and it shows some interesting combo's. I'm wondering how close this has gotten anyone. First, the bow:
Samick Red Stag
50# @ 28" draw is 27.75" or so
Center cut
16 strand FF string

Arrow one wouldnt seem to work but the calc has a +/- of 1
GT 5575
29"
3 x 5" feather
Standard components
250 gr tip
(I was using a 200 gr tip and JUST barely showing stiff)

Second arrow:
GT 3555
31"
200 gr tip
Same fletch and components
+/- waaayyy off. Like wouldnt look to work at all.

Am I trusting the calc too much? Anyone ever use similar set ups?

[awbowman]

Too long at 31" would be my guess.

I'm pretty sure you can make 35/55s work at the right length and a slightly less weighted BH if that's what you want to shoot.

Those two arrows don't seem matched in spine to me

I have never used the 3Rivers calculator, but I have used the Stu Miller calculator and once I got the Personal Form Factor set for me, things usually are very close for any combination I enter.

I shoot 50#@29 1/2" and 32" GT 5575 with 250gr up front and 3-4" feathers is perfect for my set-up!

Bisch

[Cavscout9753]

Ok thanks. Yeah I know, I was just playing with numbers for things I own on hand. Not commited to anything, though... If the 250 gr tips I have in the mail clear up my 5575's I will be tickled. Everyone told me 200's on a 5575 cut to 29" would never work, they were mostly right, though its not as far off as youd think. It just takes robotic form (which I dont have haha). The calc has 250 tip matching perfect minus some BH tweaking. If so itll be a molly-whopper of an arrow! On a side note, the calc turned the 3355's at 31" with 125's perfect as well. I dont want to kick a sleepy dog here, but is that too light of an arrow for hunting purposes? Im talking deer, pig, coyote. Im talking all things being equall as far as perfect tuning. Think it'll turn out about 425 total at 8.5 gpp. Is that asking for problems?

[jkm97]

I've used, and for me, I found that carbons with high FOC actually shot better showing several pounds weak.

[M60gunner]

I have found the calculator results a little confusing both the 3rivers and Stu's. I get closer results with a lighter arrow. When I try to get close to a 9.5 - 10 grain arrow I get real wide numbers, dynamic spine bow vs. arrow.

[Cavscout9753]

Yeah for the light set up its pretty fairly even. For heavy arrows the spread is wide. Eh, I'll just shoot them when I get everything and see for myself. Neat tool though, seeing how much small things effect arrows, like strike plate. I had no idea adjusting thickness of the plate can do so much to any arrows spine. I mean I knew it changed it, just not so drastically. May be a tunning method I turn to over constantly cutting and jamming weights onto arrows.

[Caughtandhobble]

I found the 3 River spine chart to be very accurate with my setups that bare shaft perfect, or very near perfect. I love Stu's but my new computer does not have Excel and I'm too tight to buy it.

[Cavscout9753]

Yeah, my computer skills/patience is low. The 3 Rivers one was easy to use. If its accurate, all the better. Haha. The only variable I really need to play with is the +/- 15 personal rating thing. Not too sure how that works. All in time. My goal is to just have a really well tuned set of arrows and sort of use that as a "home base" and play with different set ups from there knowing I have the formula for a good set if all else fails. I wish I possessed the words to say just how great and helpful this forum and many of the shooters on here are. I know the whole "will this set up work?" thing gets old, but theres still people who've answered it a million who are willing to repeat themselves. Great forum with great people.

[Bladepeek]

I just set up a new set of arrows for my 46# @ 28" bow, drawing right at 28".

The 3555s worked out perfect for me cut to 29.75" with a total of 186gr up front (125 gr field point, 50gr weight screwed into the rear of the 11gr insert).

I took the 50gr weight out and replaced the 125 field point with 175 broadheads on 2 of the arrows and now have bare shaft, field point and broadheads grouping together at 20 yeards, which is the farthest distance I have available right now.

[silent sniper]

I just tried the 3 rivers calculator for the first time today. I put in the specs and cut an arrow to the calculators spec and went out to paper tune it to see just how close the calculator was to real life shooting.

 My first shot through the paper was just shy of a bullet hole! I was extremely impressed and will be using the calculator from now on. A very useful tool in my opinion.SS

[Mr. fingers]

It will defiantly get you very close you just have to be honest and accurate with your  answers.