# Cape Buff ... Momentum required



## EugeneB (Mar 12, 2010)

Hi Guys,

Some background: Left SA approx 18 months ago for Aus ... looking to visit soon and perhaps take buff. Stayed in SA (Pretoria) for 20 years. Already took some plains game with the bow in SA.

My question: Requirement for Cape Buff or Aus Buff ... what type of Kinetic or Momentum required ... any suggestions welcome.

Figures based on my new bow ... IBO 330fps, #70, 32" dl and 5 grains on string ... note that my draw lenght makes a huge difference ... assuming I will shoot 150gr Ashby style 2 blade bh ...according to the figures below the 700gr arrow provides me with the best penetration ... relating to momentum formula) I am not too crazy about using KE as the indicator for penetration.

Your opinion appreciated.

Cheers - Eugene


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## Deserthuntr (Nov 23, 2008)

*Penetration*

Hi Eugene

Seems that you are on the right track. You may increase your Front Of Centre a bit. By my guess the FOC on your arrows is about 10%. If you increase it to 16%+ your penetration will also remarkably increase. I increased the weight of my arrows slightly but increased FOC from 12% to 17% and had astounding results. Alot of new articles illustrate the effect of high FOC and extreme FOC on penetration.

Hopes this helps.

Good luck.

Ian


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## EugeneB (Mar 12, 2010)

*Thanks for the info*



Deserthuntr said:


> Hi Eugene
> 
> Seems that you are on the right track. You may increase your Front Of Centre a bit. By my guess the FOC on your arrows is about 10%. If you increase it to 16%+ your penetration will also remarkably increase. I increased the weight of my arrows slightly but increased FOC from 12% to 17% and had astounding results. Alot of new articles illustrate the effect of high FOC and extreme FOC on penetration.
> 
> ...



Thanks ... I forgot to mention I will use EFOC around 25% ... have never played with this though ... hav read Ashby's penetration info and it seems to make a HUGE difference ... also plan to use the Grizzly Sticks arrows


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## Deserthuntr (Nov 23, 2008)

*Penetration*



EugeneB said:


> Thanks ... I forgot to mention I will use EFOC around 25% ... have never played with this though ... hav read Ashby's penetration info and it seems to make a HUGE difference ... also plan to use the Grizzly Sticks arrows


Great! Well then I think you are pretty settled. Maybe some of the other chaps will have more imput. Good luck!


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## Macker (Mar 22, 2007)

there is a huge thread going on right now on extreme foc, you should check it out, very informative.
i think you are definitely on the right track.......probably good to go right now.
good luck,
Jeff


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## Gerhard (Aug 3, 2005)

Will you be hunting a Bull or Cow?

For a cow your stats looks fine.

For a bull I would upgrade to at least 80# min and 850gr + arrows.

I personally would not hunt with less than 90# and 900gr + arrow.

Why would you want to spend such a large amount on trophy and travel costs and hunt with equipment that would not produce the best performance available today and at the end your Buff is killed by the PH?

Remember you need to have enough momentum in your arrow to penetrate at least .75 inch of some of the toughest hide in Africa, then you need to punch through .5 inch of overlapping rib bone and then have enough momentum left to penetrate both lungs.

You might only get a shot at 35 yards or further...

You will also be right in the bull or cow's attack zone as well...

Just my 2 cents on the subject.


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## EugeneB (Mar 12, 2010)

Thanks 4 all the info ... the figures I posted was based on a new bow ordered and not yet received (used 2 diff speed calculators based on different weights ... got the ave and worked out the KE and Momentum) 

I posted the same question on another thread and someone indicated to me that the speed calculators are incorrect ... it seems the calculators are more accurate on lower arrow weights and when it comes to estimating the heavier arrows falls way short e.g. this person has sort-off the same setup as what I have (his bow shoots the same fps on eg 400 grains) and his bow shoots a 1000gr arrow at around 214fps .... he indicated my bow should do the same ... he actually inserted his configuration into the same speed calc and it estimated 147fps ... be aware not to base your decision on heavier arrows on the the speed calcs ... obviously this changes everything for me as it seems my best penetration will be way over 700gr arrows .... I guess I will wait for my bow and do actual testing! :tongue:


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## hunter0104 (Apr 8, 2009)

Althought draw weight, arrow weight and KE is all a MAJOR factor in hunting BIG dangerous game, I will stress this. Make sure you are shooting a SHARP SHARP SHARP head. I mean if you wont shave your face with it its not sharp enough! Having been in a party with two archery hunters chasing the "black death" and seeing first hand the difference between a sharp head and an ok sharp head, you want the sharpest smoothest head possible. The bull that was shot with questionably sharp Magnus Stinger wasnt dead after 45min wait and 90yd blood trail and had to be put down (double lung). It was just the opposite with the second bull dead after 35min and 85yd blood trail. 

I know when I take a cape with archery equipment I will be shooting an 85lb Omen, with 756gr arrow tipped with a custom made cut-on contact head. 

Good Luck!


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## Big Country (Apr 25, 2003)

EugeneB, first of all.......good luck on your upcoming hunt!:darkbeer:

That said, i am not sure where you got the data tables you have provided for us, and possibly I am reading them incorrectly?

If the bows draw length and draw weight stays the same, and the ONLY thing to change is the arrow weight.........assuming that each weight arrow is correctly spined for your bow, your KE and momentum will ALWAYS increase with a heavier arrow. Your arrow speed will obviously reduce with added arrow weight, but when dealing with any practical weight hunting arrow(1500 grains and under) you will not see an arrow weight increase that will yield lower KE and momentum numbers. it just does not work that way.


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