When to spine up for weight up front?

[PathFinder]

I'm currently getting everything together for my new setup. 80 lb Hoyt Hyperforce, 27.5" draw. Arrows will be ~27" shaft length. My current plan is to use a VAP 300, 100 grain Ethics outsert/insert setup, and a 100 grain head. Total weight will be 475 gr with 15.4% FOC. Looking at Victory's spine chart, I'm just barely into the 300 bracket. I assume their chart isn't based on having this much weight up front. Has anyone been able to quantify just how much weight can be added up front before spining up?

 

[Trial153]

I think your one the cusp of being too weak. I would run 250s

 

[Bowhuntr64]

I use Easton charts and they always account for weight up front. Not sure how you can determine the correct spine without factoring in front weight.


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[PathFinder]

I definitely don't want to risk being underspined to save FOC, which is why I'd really like to stay with a 300 if it will work. Even with fairly light high modulus arrows (VAP, Element Storm, X-Impacts) I'll drop a lot of my FOC going to the 250. After running the numbers through the Goldtip and Easton calculators (they allow for 150gr point weight) it's looking like I'll need a 250. I keep coming back to the fact that a Grizzly Stik will give me exactly what I want in terms of FOC and overall weight, where a parallel shaft just can't. The only downside (that I'm aware of) is the cost. Any input on that option?

 

[Btaylor]

Might could shorten the shaft an inch to an inch and a half and add a lighted nock like a nocturnal at 20 grains. That should keep total arrow weight almost the same and stiffen up the 300 shaft. Not sure what you see in foc change but wouldn't expect it to be much.

 

[Grunt-N-Gobble]

High foc isnt all its cracked up to be. Ive played around with it using a nitrum turbo @ 70lbs and a 29.5" draw shooting 29" arrows in 300spine. 50gr inserts and 125gr points. I really dont think the spine was stiff enough. A left tear that has been difficult to remove. As i lowered the weight the tear improved.

So id guess with what you are attempting, the 300's wont be enough. But hey, you could always get 3 or 6 arrows and give it a try before dumping $$ into a dozen shafts.

 

[RosinBag]

If you have access to Archers Advantage you can use that to determine at what point FOC breaks that arrow down to when it will become to weak for you. I also agree that your arrow seems long for a 27.5" draw and that FOC should not be a deemining factor in arrow build.

 

[Brendan]

I use Software for Archers (Mac):

Pinwheel Software - Software For Archers, Tapes And Charts, Shaft Selector

You enter all your parameters and can see the effect on spine. With some quick entries, the software shows you a little weak spined at a 300. If you can lower your arrow length down to 26" - you're in the green assuming your bow loses a little efficiency from the 340 ATA rating.

You might be better off running a 250 and bumping your head up to a 125 grain, but to be honest, I'd go for a heavier arrow overall than the victory. Something like a 5mm Axis with a 75 grain brass HIT insert, maybe a FMJ?

To be honest - i'd pay for the software. Cheaper than one set of arrows that don't work for you.

 

[EsteemGrinders]

Not trying to be rude but I think you are over thinking this. FOC is not as big as most make it out to be. I have spent more hours then I care to admit crunching numbers with Archers Advantage. For my arrows now I get way more speed and the same KI as I would with a much higher FOC arrow. I suggest getting the software and playing with the numbers for your self.

 

[PathFinder]

I've decided to just download the software and pay for it. It would have saved me hours by now. I know the GrizzlyStik setup will work out, I just need to decide if I want to pay for them. I want to do some destructive testing on angled hits with low and high FOC arrows when I get everything all set up. I'll post it when I get done.

 

[PathFinder]

Archer's Advantage is telling me that the 300 is ok with a 90 grain insert/outsert and a 125 grain head, at about 481 gr total. I'll probably order a few and give it a shot.