Primitive Archer
Main Discussion Area => Arrows => Topic started by: Don W on June 27, 2021, 06:37:10 pm
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And when is it to heavy (keeping hunting big game in mind)
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I'd say anything over 10grs per pound of draw weight would be a heavy arrow. Consistency would be a limiting factor in an arrow's physical weight. 1000grs wouldn't be too heavy for some heavy game like water buffalo.
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1) What are you hunting?
2) What is the draw weight of the bow?
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Whitetail and 45, 50 or 55#.
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500gr to 600gr would be about average for a hunting arrow for 50# to 60#@28". Anything over that I would consider heavy.
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Whitetail ribs break easy, easier when hit by a cut-on-contact broadhead.
10 grains per lb of draw weight will serve you just fine. If you were hunting something with a heavy coat, like black bear, I might suggest a heavier arrow. If you were hunting wild hog, I would definitely suggest a heavier arrow to get through that tough hide and armor-like shield under the skin.
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Anything under 2000 grains and you might as well be throwing toothpicks. ; )
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A dead heavy arrows used to a limited extent with the English War Bow were like mini javelins, 36" or longer and a half inch thick at the head tapering back to about 3/8" at the nock. With a very heavy head.
I figure these were meant more for dropping a charger in its tracks than anything else. Much like the large caliber muskets and horse pistols , since those were shear overkill when used against humans.
Arrows that size dropping in among lightly armored infantry would be terrifying.
Many primitive tribes used and still use arrows even longer and heavier.
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If you have not yet found Mr Ashby's foundation, you'll find useful info there.
https://www.ashbybowhunting.org/
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If you have not yet found Mr Ashby's foundation, you'll find useful info there.
https://www.ashbybowhunting.org/
Thanks for that. I had not found it.
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Thanks Knoll, interesting read...As a hunter you learn to appreciate the heavier side...Kinetic energy along with perfect flight is the key for penetration...
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Yes, achieving great arrow flight is so so important.
Thanks to Dr Ashby's work, I've been persuaded that it's momentum at impact point, rather than kinetic energy at bow, that is determinant re penetration.
And recent work by Ranch Fairy (YT contributor and member of Ashby Foundation) has shown that kinetic energy out of the bow are closely grouped within wide range of arrow weights . . . but momentum at point of impact is widely dispersed from lightweight (less) to heavy (more) arrows.
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Knoll, I have sat an thought many times on the impact down range...There is a perfect weight combination for each bow / arrow set up where the weight of the shaft doesn't impede the bows performance to push and become to sluggish...That is if one can find that "magic number"..I ran a few tests years ago changing point weight and measuring penetration on a new soft block type target. My findings at the time with my set up @ 57 lbs. was that the upper 600's gave me the deepest penetration @ 15 yds...That was just some back yard stuff and not real scientific...There are so many variables that come into play that I could go bonkers...I even found myself at one point carrying a small snuff can of lard to dip and coat the tips of my stone points in to keep the entry slick...Stone, pitch and sinew are not naturally slick against wet, sticky/bloody, hairy and flexible animal hides...I have found through bow hunting well over thirty years with compounds, trad and then what I would consider Abo, that the heavy shaft gives you more "momentum of impact" down range agreed...
It would be interesting to see maybe a chart where someone has tested a wide range of different weight shafts penetration from a given weight bow to determine best penetration from a given yardage...That would take some work, so many variables to consider...Perfect flight is a must...Bare shafting is key for me to achieve great flight
Thanks again for the link to Dr. Ashby's work...
Don
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Donald, many of your conclusions are the same as Dr Ashby. And he (and his colleagues) had the advantage of being able to carefully study literally hundreds of fresh kills. :OK
And, unlike me :), Ashby had the knowledge of physics to explain the "whys".
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With an efficient 45# bow 550 to 650 grained perfect flying arrow shafts sharpened to a razors edge flying 165 to 170 fps. the deer does'nt have a chance [an elk either] if it's put in the sweet spot.If I had a choice between using a 10 grain arrow or a 12 to 13 grain arrow I'd use the heavier every time for hunting.10 grain arrows off a 50# bow are considered target shooting arrows by me.
Dr. Ashbys' findings are sound as brick of gold.Many including me have adopted his findings.
Perfect for us under 20 yard shooting hunters.
Another benefit is that most hunting type bows if over built a tad become more efficient shooting heavier arrows.
When deer hunting it's all about putting the odds in your favor in every catagory of hunting.
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A 10gpp setup has high odds of ethical kill if impact is in sweet spot.
But, as you say Ed, with setup you describe ya have good odds of kill even if it's a not so sweet spot.
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Yes your right knoll.Your talikng in a perfect world with a perfect shot though.Many times it just don't work that way.Deer are still awfully tough critters running at 90% nervous break down while cruising the woods.Always on the alert.A foul shot most times is an investment into a long drawn out retrieval.It's still all about putting an ethical clean shot through the heart/lungs/or liver or all three at the same time and heavier arrows put the odds in a hunters' favor.The vitals on a deer are actually bigger than what these 3D forms show.Proper angling of shot is super important.Lots of variables.One reason why it can take a lot of patience to get that perfect standing shot while the deer is mostly relaxed and without spooking the deer.Probably why I've never had a deer jump the string on me either.The self bow is the silent assassin.
I never shoot at a deer looking right at me in the stand with a bow.Even if they are so close I can see their eyes blinking.Using a gun is a different thing.
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I would love to have a bow that would shoot a 600 gr arrow at 170fps! I make my own arrows, and most are in the 600 gr range. I'm working on getting them to go faster, but for now I'll need to settle on 140-150 fps.
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That'll still do the job easily Don.Especially under 20 yards.Good luck with your hunting.
If you've ever seen these hunting shows where the hunter will say over his dead deer that he could'nt be happier after shooting it with a gun at 150 yards.He does'nt know what he's talking about and missing out on what it feels like killing deer with a self bow and self arrow.
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I would love to have a bow that would shoot a 600 gr arrow at 170fps! I make my own arrows, and most are in the 600 gr range. I'm working on getting them to go faster, but for now I'll need to settle on 140-150 fps.
For what it’s worth Ashby puts 650 grains as a sort of “magic number” above which you get a jump in penetration ... I don’t know how exact this figure is or why... he also puts much importance on an arrow being 19% FOC and above. For me, I have struggled to get this FOC at any weight below about 650 grains with bamboo arrows... they seem to go hand in hand.
With more FOC, in theory, you need less fletching to get good broadhead flight - and Ashby himself doesn’t use an offset fletch ... so again - in theory - you trade some speed for a quieter arrow...
On my lighter bows (45lbs) they do feel a little slow in flight for my liking, but if one goes on the principle that you aren’t going to shoot anything over 20 yards - then for me at least, at that distance, they are pretty much point on for me (I shoot 3 under) ... so I wouldn’t feel handicapped by an arrow of this weight at all...
In addition, I also think people totally over estimate the idea that a slightly faster arrow is going to compensate for an animal jumping the string or moving as you take the shot. I would trade penetration over arrow speed any day.
Ashby’s reports are the real deal - and he’s done the hard work - so I certainly pay a lot of attention to them.
One final point he makes - which I think is very true is that “mass/weight belongs to the arrow - you can’t take it away - but the instant your arrow hits something it’s speed drops rapidly” ... so basically in your momentum equation - mass x velocity - you are better off making up the momentum with mass over velocity, because you can’t rob the arrow of the mass component as soon as it hits something...
You may enjoy this article by Ashby on hunting in Papua New Guinea where I believe some of the arrows Ashby handled were up to 4000 grains!
https://journalofmountainhunting.com/primitive-bowhunting-lessons-papua-new-guineas-png-bows-and-arrows/
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I am not close to caught up on the reading, but the links are appreciated and I'll definitely be going through them all. It may not be until winter sets in, and maybe even longer, it all looks pretty in-depth.
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Correct Tommy D about FOC for penetration.
Carbide arrows are easy to get balanced FOC 6" from the tip.With wooden full length tapered dogwoods maybe 9 to 10 inches balance from the tip.Which puts them in the high teens maybe low 20's percentage wise FOC.Flying clean and true quickly from the bow.A real bone busting shaft IMO.
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I am not close to caught up on the reading, but the links are appreciated and I'll definitely be going through them all. It may not be until winter sets in, and maybe even longer, it all looks pretty in-depth.
Here is a summary by Ashby (with real world numbers) of the relationship between mass and velocity - for one of his bows.
Also, some examples of how when you use “momentum” as the measure of an arrow’s lethality (over Kinetic energy - as is the norm in many circles), you can better understand how a bow and arrow can be just as lethal as a firearm.
(https://i.imgur.com/mIY4cRi.png)
(https://i.imgur.com/E2mXPdY.png)
The whole article is here https://journalofmountainhunting.com/part-iv-the-physics-of-arrow-penetration-by-dr-ed-ashby/