Need help w/ buffalo arrow for 76# recurve

[Don_G]

I have designed a new broadhead for a Cape Buff hunt in July. My PH wants to use them for water buff in May. The broadhead is 264 grains, the adapters are 111 grains, and a minimal 2.5" aluminum foooter will weigh 25 grains, so the head assembly weight will be near 400 grains.
 
I have NO experience tuning arrows for trad bows, and he will only be in town a few days, so I need some help getting things ready.

He is sort of a normal-sized guy, so I think he's drawing 28-29".  He uses a 76# Robertson Stykbow recurve. The broadhead has to mate with a 5/16 shaft. (And by 5/16 I mean .3125 +/-.001 inches.) As an example compound arrows are GoldTip Big Game 200 Kinetic Pros footed with 2.5" of 2012.  The 2012 section sticks up inside the broadhead and sets the shaft/head alignment, so basically I can only use 20XX shafts or shafts that can be footed with 20XX.

He wants a 950 grain arrow. I have Goldtip Big Game 200 Kinetic Pros, the 300 spine Axis STs, and can get 340 spines if I need them. I have weight tubes for the .204 ID arrows to get from near 750 grains up to near the 950 he wants.  I have the proper 20XX arrows to foot the 200, 300 and 340 spine shafts I have in hand.

Can anyone please give me a starting point on which arrow to star with, and how long of a footing to use?

Any advice appreciated, but direct experience is desired!  

[L. Perry]

Might try easton full metal jacket dangerous game, they come in 250 spine and 300. My 250 are just right with my 86lb. recurve with 75gr. brass insert and 150 grain broadhead.

[L. Perry]

They finish out right at 800grs. With that much point weight should get you to 950. Might not even need the footing.

[pdk25]

I have gold tip kinetic 200 bareshafted for me with my morrison dakota that is 75# @ 28" drawn to 29" using 100 grain brass inserts and 325 grain tips for a total of 425 grains up front with 1 1/4" 2013 external footing on the front.  The arrows are cut to 31".  The total weight without fletching is almost exactly 800 grains.  Probably finish a little over 830 with fletching and wraps.  It sounds like he wants another 100 grains.  Sounds like with his setup if he needs another 50 grains or so if he uses 100 grain brass inserts to get the weight where he wants it.  Maybe a 50 grains brass insert inside before the 100 grain and start with the arrow 32" and slowly cut it down to get it where you want it.  Tought to say without him here, but it might be a start.

[Benny Nganabbarru]

Grizzlystik Safari - they aren't perfect, but they're good.

[straitera]

Buffalo arrow? Man, wish I could help. Sounds like a great prelude to a great trip! Like to see pix of the bow drawn if possible. Heavy lb shooter here but appreciate your commitment regardless! Good luck!

[Don_G]

Thanks for your help, suggestions and patience. I am not used to the dynamic spine requirements of a trad bow. The Dauntless broadhead looks like this. Maybe the pics will help make sense of the first paragraph, and explain the limited arrow size selection allowed.

               

               
   

The assembled (less fletch) uncut GT BG200KP arrows with 2.5" Eclipse 2014 (not 2012 as first post said) footer come in at 790 grains. (pdk25's experience gives me hope this arrow might work out, and L.Perry's makes me think 250 spine might not be enough for this head weight/arrow weight.)

If I try to start with this arrow, I have to add 160 grains somewhere. I think I can do this either in a lump just behind the mandatory 111 grain SS custom adapter (using 150 grains of brass??) or I can add distributed weight along the length of the shaft using tubes. What would be the relative effects on arrow spine?  In other words how much spine tuning will these two choices give me?

I designed the head to improve assembled arrow integrity, so I am a bit worried about stacking stiff weights up front that are not structurally tied together.  I'm afraid the arrow will tend to break at these stress concentrators. An aluminum footer across these will help, but may not be sufficient to prevent breakage on heavy bone hits.

I know I can't arrive at the final arrow without him here, but I am hoping that with your help I can shorten the process and have all the supplies on hand.

[Benny Nganabbarru]

The weird thing is that those Grizzlystik Safaris really do suit a wide range of bows and draw weights. And I have found that what Ed Schlief said about them is true: "Just fletch 'em up and shoot 'em!"

[Don_G]

The problem is that the Dauntless head is designed around 5/16 arrows. The Grizzlystik arrows are non-starters simply due to dimensions.

[slivrslingr]

I've been following your post about this system on AR, some interesting results you've found and that broadhead is pretty cool.  I think for tuning your friends bow/arrow, I'd just build up an arrow from each of your spine groups and go from there.  The 340's will likely be too weak, the 200's too stiff, but you won't know for sure until he shoots them.  With all that weight up front and the required footing, conventional wisdom doesn't really apply.  Hopefully he is with you long enough to come up with a combo that works.  I'm trying to come up with an arrow for my heavy recurve and while I'm close, the perfect combo hasn't been found.  Good luck, I'm looking forward to seeing what you come up with!

[Don_G]

That's basically what I intend to do: find the stiffest arrow that is underspined when weighted up, then add footer length 'till it works.

[ozy clint]

interesting broadhead. the 1st i've seen where the blades aren't on the same plane. which leads me too this....

since it's a single bevel do think it might rotate better in flesh and bone if the bevels were on the opposite side of the blade to which they are on now? the way the blades are offset wouldn't they rotate easier in the opposite direction to they way the bevels will make it rotate??

as for arrows, maybe a GT big game 100+?

i agree with slivrslingr. i think some trial and error will come into play here.

[pdk25]

I think the GT big game 100+ will be too weak when the requisite front weighting is applied, and I think as long as you don't cut the 200 kinetics too much before you start, that they may work.  If it was me, I would start full length with the 50 grain and then 100 grain brass inserts, put your external footer on, get a set of 3 of the 300 grain glue on brass field tips from tuffhead and put 75 inserts inside, then cut down to bare shaft.  Good luck.

[Don_G]

Originally posted by ozy clint:
interesting broadhead. the 1st i've seen where the blades aren't on the same plane. which leads me too this....

since it's a single bevel do think it might rotate better in flesh and bone if the bevels were on the opposite side of the blade to which they are on now? the way the blades are offset wouldn't they rotate easier in the opposite direction to they way the bevels will make it rotate??

The way the blades are offset let the edge run unbroken all the way around the head. The resulting tip is a thing of beauty, and has come unscathed through some ridiculous tests.

I'd rather keep this thread on tuning issues.

As mentioned in an earlier post, I'm a bit afraid of stacking stiff weights behind the adapter since I think it will make breakage on impact more likely. They also dramatically affect the arrow spine both by stiffening the arrow (increasing spine), and adding tip weight (tending to decrease spine.) 160 grains of .204 diameter brass would be a couple of inches long, and add a hinge point between the brass and the stainless steel glue-in adapter.

Something memoryless, soft and heavy behind the adapter would help keep the high FOC as well as having a more predictable effect on spine.  Would lead wire have too much memory? (Tend to stay curved after arrow flexure?) If I could find some way to keep it in place mercury would be perfect for adding non-structural weight at the tip.

The weight tube would add memoryless weight, but it is distributed weight that pulls the potential 27% FOC down to 15% or so.

Too many choices and too little time!

[pdk25]

Yeah, by adding more adapters you would need to keep the arrow longer initially before cutting it down to account for the stiffening factor.  As far as breakage on angled shots, I think that is more a factor of arrow weight due to leverage factors, but I could be wrong. Wouldn't mind that theory being tested out.  Not sure how you could secure wire without it having the same effects as an insert, but good luck.

[Terry Green]

[Forrest Halley]

The ABS is probably the ticket. I'm running one with 250 gr three blade at 29" BOP and the brass adaptor with no extra weights. Total arrow weight is 850gr on average. They work in a 95# recurve and 100# longbow. The safaris are floppier than they'll admit and no matter what they tell you...treat it like a normal .250 spine arrow in stu miller. It will do well at 29" with all that weight you're planning on, but you'll either need weights on the inserts or play with the weight of the screw in adaptor.
Edited to acknowledge that your system won't work with the Grizzlystik.

With respect to the GT big game: it appears to be useless as a traditional big game arrow. Way too light initially and the add on weights kill the stiffness. You'd have to foot to get anywhere near your requirement.

Possible solution:
PSE Black Mamba .313" dia. at 29.5" with 264 grain point, 111 grain insert and your spec'd footing comes out at 1022gr and 76.5 dynamic spine but only 18% FOC. 29" would get you 83.3 dynamic spine.
Best of luck.

[Don_G]

Forrest,

I'll have to check out the mamba. Never heard of it before.

I got to looking at the GT Kinetic series because I was trying out Ashby's EFOC. Seems to work fine in my 73# "other" bow at the "natural" 750 grain weight.  

I don't blame Rainer at all for wanting a 950 grain arrow on Cape Buff, but I was wondering how it'd work at 750 grains.  Ashby had good results at that weight with a UEFOC. At 750 grains the FOC is 27% - not Ultra EFOC, but pretty respectable.  They work well in bone tests, too, penetrating 2.5" of cow bone every time.

Rainer threw me a curve, though. He forgot to bring the bow!  Since I don't even know what shaft to use I can't give him the full-length shafts and let him trim to tune in Tanzania.

[Michael Baker]

Don G

Mate I would have another talk with Rainer as I feel that any weight over 800grn is fine enough to take a Cape Buff out of that bow. If you have the arrow well set up and flying great at 800+ and only flying average at 950 the 800+ will work better every time. Build the arrow you want and get the best performance flight and you will be on a winner. Remember hit the spot and not have to be worrying about flight and all will work out fine.

Cheers
Mick

[old_goat2]

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