Arrow selection for giraffe hunt

Discussion in 'Bowhunting Africa' started by wanderingjim, Apr 27, 2018.

  1. wanderingjim

    wanderingjim AH Member

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    Hey fellow arrow flingers. I am hunting a bull giraffe in a few months time and was wondering on arrow selection, or more importantly arrow spine selection.

    I am using my hoyt nitrum at 29inches and 72lb.

    I am using 200gr or 180gr german kinetics up front. And im using the easton dg fmj shaft.

    Do i go with the 250 or 300 spine shafts given the poundage and speed of the bow?

    Im leaning to the 300s at this stage but please anyone who has used thses shafts with similar poundage bow let me know.

    Thanks
     
    Last edited: Apr 27, 2018

  2. firehuntfish

    firehuntfish AH Fanatic

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    You need to shoot both spines and see which one flies the best from your set-up.... If the arrow is under-spined, you will likely have a tough time tuning it to fly true. The most common behavior to look for is "fish-tail" flight where the arrow seems to wobble or yaw from the rear during flight. This can be best observed by a slow motion video or the use of a lighted nock when practicing. I would also suggest paper tuning both shaft options.... Get as close as you can to that "bullet hole" in the paper.

    I used a very similar set up to take a buffalo and giraffe with a 175 Grizzlystik shaft, with a 315 grain Bishop broadhead at a total arrow weight of 975 grains. At 72lbs of draw, you have plenty of bow. It's going to be the total arrow weight and its foc that will make or break you on the effectiveness of your set-up. I would suggest building your arrow out to at least 750 grains with 20% or more foc, and it wouldn't hesitate to go as heavy as 975 grains. Giraffe have a thicker hide at the shoulder than a Cape buffalo and a bigger bone structure. The only thing they do not have are the overlapping ribs of a buffalo..... Even with that set-up, your PH will likely have you try and take a frontal shot between the points of the shoulder.

    Good luck & have fun!
     
    Last edited: Apr 28, 2018
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  3. BRICKBURN

    BRICKBURN SUPER MODERATOR CONTRIBUTOR GOLD BENEFACTOR AH Ambassador

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    Spot on.
    Those big solid broad heads take on a life of their own.

    I had to change fletching (4 inch feathers) to balance my arrows flight.

    Good luck & have fun!
     
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  4. G Skinner

    G Skinner AH Fanatic

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    Tho I've never shot a giraffe my bow is similar to what you are shooting .I'm currently shoot FMJ 300 which is what the Easton arrow chart indicates ....... I've always felt it is their job to know the best spine for a set up .
    Glen
     

  5. firehuntfish

    firehuntfish AH Fanatic

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    The spine reference charts provided by the manufacturers are a guideline, not Gospel. They will get you close, but there are too many variables to consider in the set-up to assume that the spine suggested will always be the correct one....This is especially true for those set-ups that are on the border between two spines. Near perfect arrow flight is the only way to confirm the correct spine.

    I can tell you from my own recent experience in building arrows for my buffalo hunt that even the experts are off once in a while. Alaska Bow Hunting Supply (Grizzlystik) offers a "test pack" of two different arrow spines to try out before you commit to a full order of arrows. The technicians were very confident that the best spine for my set-up would fall between a 320 and a 240 with them being 99% sure it would be a 240. After lots of frustration, consultation, and tweaking, they ended up sending me a 170 which flew like a dart.... It shouldn't have been the correct spine but it was the only shaft that punched bullet holes in the paper out to 40 yards.

    You may be surprised to know how many experienced bow hunters confuse tight groups with near perfect arrow flight and proper tune. They are not one in the same... You can shoot tight groups out to 40 yards and beyond and actually have poor tune. Even an out of tune arrow will usually deliver enough energy to poke a hole in the animal, but this is problematic especially for those shooting lighter poundage bows who do not have the extra energy to squander. It's also very problematic for hunting big game which requires every ft.lb. of energy possible to be converted into momentum applied to that arrow.
     
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  6. Lee M

    Lee M AH Fanatic

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    Well said. Test a few and see what flies best. I am also considering a giraffe with my 29” draw, 70 lb Halon 6 32” in July assuming I can get good flight and accuracy. I have some fmj DG and regular FMJ with weight inserts that I made I made 2 years ago for a giraffe hunt but didn’t take a giraffe. I will test with 200, 250 and 300 grain 2 blade VPAs.
     

  7. BigJohnx13

    BigJohnx13 AH Senior Member

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    Here is a report of a hunter that was written in a book


    I hunted a giraffe with 80 foot-pounds (70 pounds draw weight, 30" draw length, 800gr @ 212fps, 210gr Silver flame BH, Ro=4.3). The broadhead required according to the model 88 foot-pounds (50 foot-pounds just getting into the chest cavity). The experiment was specifically designed to test the predicted penetration. This is not a chance I would normally take, but my PH was taking aim with me, and if the shot looked even slightly ineffective, he was waiting for the instruction "Shoot". But at 43 yards the hit was clean, just above the heart, and penetrated about 25" - no need for the .375. The giraffe went down after about 100Y. The predicted penetration was 29". This experiment again confirmed the model. (Note - hunting a giraffe again with this setup is NOT recommended, rather use 800gr at 90 foot-pounds!!!)


    Larger game is generally slower to move, and 30Y is quite acceptable for the large antelopes. For Giraffe and buffalo, 40Y is not unrealistic. The maximum suggested hunting distance is not a function of the hunter's accuracy, but indeed of the animal's reaction time (and size of vital organs) vs. the speed of the arrow.

    NB. At the generally accepted arrow velocity of 250fps, animals at 20Y have about 0.2 seconds to react to the sound and animals at 40Y about 0.4 seconds.


    If the arrow mass is 800gr, arrow speed is 188fps, and Ro is 8lbs, the penetration is around 40 inches. According to the optimum recommendations on mass and velocity, this would qualify as a perfectly acceptable hunting arrow for all categories. In reality this velocity would provide the animals 0.280 and 0.580 seconds at 20 and 40 yards to react. This is in regards to reaction time, as (un)acceptable as shooting a 250fps arrow at an animal at 60+ Y. Therefore, the suggested decrease in maximum hunting range of arrows that does meet the optimum speed recommendation with the adjusted speed, but in reality is slower, is suggested in line with a reaction time of 0.2 to 0.4 seconds. Another factor plays a role in defining maximum distances. Arrows loose speed due to friction in air, roughly at about 1% per 10Y. An arrow at release may have 40ft.lbs energy but at 60Y it may only have 35ft.lbs (for 570gr at 195fps). Arrows shot to an elevated target loses speed more quickly in relation to the angle. Arrows shot to a downhill target loses speed much slower again. However, when staying within the recommended speeds, this effect is overshadowed by accuracy and reaction time compensations.


    Hunting tips for above 800kg, buffalo, giraffe, hippo etc., a two bladed broadhead of at least 1.25" is suggested, without bleeder blades.


    Zimbabwe regulations. Giraffe and Eland Minimum pull 35Kg or 77 pound min arrow weight 700gr (45 grams)
     

  8. jeff

    jeff AH Elite

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    Many of the formulas on charts don't take into consideration how important a high FOC is on penetration. The same wight arrow will penetrate considerably more if the weight is FOC 20-30%
     

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