# Rpm 360 tuning @ 28"/70# arrow spine and high FOC



## enewman (Jun 5, 2007)

I'm shooting a mr5 at 68 lb at 26.5 in. Arrow is the velocity 300. I'm shooting a 100 gn insert with 145 gn tip. There around 505 total weight. So far there shooting good. I'm doing walk back tuning today. My foc is around 20+. I have not really checked yet


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## enewman (Jun 5, 2007)

My foc is 21.5


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## tylerm86 (Aug 26, 2012)

That's good to know I've been debating on leaving insert/brass weight at 12.4 grains(Gt insert) and 50 grains (the brass weights I have). For total tip weight of 187.4 including the 125 gr tip for a little more foc IF it would spine out okay......I just don't know lol I have a dozen velocity 300 shafts and all the components I just hate to waste a shaft testing spine ya know?


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## Huntinsker (Feb 9, 2012)

No you'll be underspined. Read through this thread. I ran a lot of numbers in OT2 for another member with similar specs. http://www.archerytalk.com/vb/showthread.php?t=2276460


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## tylerm86 (Aug 26, 2012)

Damn I'm running a 495 grain total weight axis 300 now at 27.75" nock groove to insert with 25 grain insert and 35 grain brass weight along with a 100 grain tip for 160 grains up front and it shoots bullet holes.........I haven't tried to broadhead tune yet....I just was going to build these GT velocity 300's for a bit more speed.....


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## enewman (Jun 5, 2007)

I can not tell you if your under spined or not. I do not use the programs. 
You will need two bare shafts. Leave full length 
Take them and install the 50 gn inserts and tip weight your going to use. 
Set center shot, several methods. Choose the one you want to use.
Make a vertical line on target
Shoot the line at 3 to 5 feet and adjust your sight till hitting line. 
Now back up to 10 yards shoot two arrows at line. Should be to the right of line. Week arrow. 
Start cutting arrows down. Make small cuts. Until arrows are on line
Back up to 15 yards do it again then to 20 yards. 
As long as arrows are no shorter then you want and there close to the line then the arrows are spined correctly 

Now fletch and do your walk back tuning. 

Go to tuffheads Webb page. Look at dr ashby how to tune a high foc arrow. Better explain then I did.

This is my first three shots at a 100 yards doing this set up

Pic is sideways. The left side of pic is top. The center of tape is 5"x6"


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## tylerm86 (Aug 26, 2012)

Hmmmmmmm


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## threetoe (May 13, 2011)

I put your numbers in OT-2

Here's what it calculated.
441 Grains
300 FPS
16.5% FOC
Perfect spine

Right smack in the middle of the green


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## Huntinsker (Feb 9, 2012)

threetoe said:


> I put your numbers in OT-2
> 
> Here's what it calculated.
> 441 Grains
> ...


You did something very wrong then.


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## enewman (Jun 5, 2007)

Can you run mine just to see what the program is. Monster mr5. 68 lb 26.5 draw. Gold tip 300 velocity. 26.5 long 100 gn insert 145 gn tip. Flex fletch ffp 360. Arrow weights at 505 to 508. And measured foc is 21.5. 5/16 meta peep and loop. Total on that is 12 gn Thanks


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## Huntinsker (Feb 9, 2012)

enewman said:


> Can you run mine just to see what the program is. Monster mr5. 68 lb 26.5 draw. Gold tip 300 velocity. 26.5 long 100 gn insert 145 gn tip. Flex fletch ffp 360. Arrow weights at 505 to 508. And measured foc is 21.5. 5/16 meta peep and loop. Total on that is 12 gn Thanks


If you're running 80% letoff, you're .014ish inches weak. That's using 26.5" carbon to carbon. If you're measuring from the valley of the nock, you're just barely in the good range if you have a 26.25" carbon to carbon shaft. Drop to 125gr point and your well into the "good" range.


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## enewman (Jun 5, 2007)

I'm not saying the program is wrong at all. I also want to think you for running the program. Doing the method by dr ashby to find correct spine with bare shaft my arrow is good. I have only done walk back to 20 yards. But it's good to that point.


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## Huntinsker (Feb 9, 2012)

enewman said:


> I'm not saying the program is wrong at all. I also want to think you for running the program. Doing the method by dr ashby to find correct spine with bare shaft my arrow is good. I have only done walk back to 20 yards. But it's good to that point.


You're not way weak so a bareshaft with that much FOC should fly pretty well if you can tune at all. A huge FOC can correct some flight problems that a low FOC arrow will show. If you had a longer DL and had that much weight up front, you'd probably have a lot more trouble.


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## enewman (Jun 5, 2007)

I'll try a 125 tip tomorrow. If need be I can cut the arrows down. The arrow is in front of riser. Part of the 145 gn tip is like hunting hogs with zwickys. Cuts down on cost. I also don't mind turning down to 65 lb if need be


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## 32Ballew (Mar 29, 2014)

Im shooting grizzlystik e-foc 250's at 29.5" with 3" trueflight feathers, tuffhead bh @ 710 total grains and 25% foc ,out of my 70# rpm 360 with 29" dl at 241 ft/sec. tuned in 3 shots. couldn't ask for better flight. Crazy quiet. Elk only for me.


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