Penetration, a product of many factors

4fletch

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I did some testing this summer with three groups of arrows. The goal was to just build three sets of arrows that a;; had the same end weight using 100, 125, and 150 grain fixed blade broadheads. While doing so I noticed the trend had swung from one end to the other since i had last been hardcore into bow hunting. I took a couple years off. Full disclosure I think any end of the spectrum is kind of a waste, and i also know you can get the job done with a stick and string shooting a stick with a small light rock on it so there is that.
But i am annoyed when people make unfair comparisons and declare a "winner' so here we are.
I used 3 fletch on the FMJs in the tests but switched to a four fletch i made and the result was the exact same. I have also witnessed the opposite of my findings in an uneven bag medium so there is that. All arrows were 5mm shot from the same bow. At the same distance. The FMJs had 125g heads. The blue wrapped white fletch axis had 75g ss inserts and 100 grain heads. In an even foam medium "normal" increases in FOC, or point weight if you will are not enough to overcome the friction reduction advantage the FMJ enjoys.
I really thing claiming one metric like FOC is the be all end all is silly. You can overcome disadvantage by compensating in another metric. Balance i think is key.
These tests do not "prove" anything other than in this comparison at the same overall weight in this medium that an arrow with a lower gpi and 175 grains up front did not dig as deep as a heavier gpi arrow with 125g up front. A significant FOC difference. Could you wax up the axis and get it close? Perhaps. But you could also wax up the fmj.
 

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Beendare

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Ugh Oh, Ashby and the Ranch Fairy have some pretty devoted fans that have drank a full dose of the FOC Kool Aide....they will son be by to set you straight- Grin

My experience; FOC is a factor thats WAY down the list.
Perfect arrow flight is key paired with a very efficient BH gives even my anemic trad setup pass thrus on almost every animal...including moose.

BTW, welcome to the forum. FYI, Its a pretty savvy crowd here that isn't fooled by some of this internet silliness.

>
 
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4fletch

4fletch

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Ugh Oh, Ashby and the Ranch Fairy have some pretty devoted fans that have drank a full dose of the FOC Kool Aide....they will son be by to set you straight- Grin

My experience; FOC is a factor thats WAY down the list.
Perfect arrow flight is key paired with a very efficient BH gives even my anemic trad setup pass thrus on almost every animal...including moose.

BTW, welcome to the forum. FYI, Its a pretty savvy crowd here that isn't fooled by some of this internet silliness.
Thank for the welcome. I like the hows and whys as much as the shooting and building arrows.
 

Rob5589

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I've listened to a couple of podcasts on Kifarucast that had Troy (RF) on them. While he does push some extreme ideas, he admits that he found somewhere around 550 taw and 20% foc was where he saw some significant penetration increases. Anything beyond were incremental. He also acknowledged that he hunts short distances, and really only shoots hogs, and that an arrow somewhere in the middle is probably best out west/at longer ranges. Perfect flight, structural integrity, broadhead sharpness, were the big takeaways.
 
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4fletch

4fletch

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As we all do. And foam is not a good penetration indicator.
Its a consistent medium. Ballistics gel is not a good analog of the human or animal body either. It was designed to be a constant. It was designed and used to show the difference between one bullet and another. Same idea for my foam comparison. I am building a jig to hold something like Paul Harells meat target for some future tests, that said inconsistency in bone, fat and muscle may be an issue.
 
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4fletch

4fletch

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Ya, but it will also show really light fast arrows penetrating more than heavy slower arrows that were all shot out of the same bow. And we know that the penetration potential is much greater for the slower heavier arrows given all else equal.
No, that is not the way that works. In the two targets i have to double up on my buddies 410 grain arrows moving at 300fps do not come anywhere near the penetration of my 530g at 260fps. Foam works on the entire body of the arrow to apply friction. Now you can use a gold tip or larger style head to limit shaft friction in foam, but what you said no. Not in my experience. It comes down to overcoming friction. And that is the goal in pen. From the head to the shaft to the fletchings.
Pic below is an example. With rounded heads i blow through dense foam to the point chunks blow out while he gets stuck halfway in.
 

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5MilesBack

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There are a lot of posts over the years that have guys showing their lightweight fast arrows of similar diameter to their slower heavier arrows, and the light fast ones penetrate deeper in the foam. I've even seen that with my ultralight and very heavy. I shoot 75lbs at just under 33" draw.

But you're right.......penetration is a product of many variables. But that's why just shooting into foam as conclusive results doesn't work.
 
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4fletch

4fletch

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There are a lot of posts over the years that have guys showing their lightweight fast arrows of similar diameter arrows to their slower heavier arrows, and the light fast ones penetrate deeper in the foam.

But you're right.......penetration is a product of many variables. But that's why just shooting into foam as conclusive results doesn't work.
Feel free to provide some evidence to back up your claims. Then we can sort out what variables were at play. "Nuh uh" really can no longer be accepted in this industry. Too many people holding back progress.
(you will notice my examples show the same thing even when switched positions in the foam, it would be too easy to shoot a worn out spot ands make claims)
 
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4fletch

4fletch

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That's the problem.......it isn't "evidence" when fast light arrows out-penetrate slower heavy ones in foam.......as much as many want to believe it is.
No friend, you provide some evidence for what you are saying. Here is that same target when it was a bit newer. There is not a second target behind it. As these arrows did not need it. This person was shooting at over 300fps and the arrows were near 400 grains. That same target had to be turned sideways as my FMJs at 530 and my Axis at 530 would bury up to the nock. (bury the fletch) As i said, i have not seen what you are saying to be true.
Pic one 300fps (second pic FMJs heavy and slow)
 

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Page Master

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No friend, you provide some evidence for what you are saying. Here is that same target when it was a bit newer. There is not a second target behind it. As these arrows did not need it. This person was shooting at over 300fps and the arrows were near 400 grains. That same target had to be turned sideways as my FMJs at 530 and my Axis at 530 would bury up to the nock. (bury the fletch) As i said, i have not seen what you are saying to be true.
Pic one 300fps (second pic FMJs heavy and slow)

Depends on the foam. You're getting awfully worked up over something trivial. In the end, foam isn't an animal and field points aren't measured equal. Seems like that is what you're both saying. My 470g arrows going 280fps don't shoot through foam, but guys I shoot with have 390g arrows going 315 that blow through targets. Does that mean they have more momentum and will out penetrate me on an animal? I don't think so.
 

MattB

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Foam is not a great medium for testing arrow penetration in my experience because different shaft materials/finishes can have a pretty wide range which can effect penetration. Ballistic gelatin would be a much better medium.
 
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4fletch

4fletch

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Depends on the foam. You're getting awfully worked up over something trivial. In the end, foam isn't an animal and field points aren't measured equal. Seems like that is what you're both saying. My 470g arrows going 280fps don't shoot through foam, but guys I shoot with have 390g arrows going 315 that blow through targets. Does that mean they have more momentum and will out penetrate me on an animal? I don't think so.
.583 vs .545 for the light guys... I doubt very much they are the same diameter or material/shape as the momentum diff is nill.
I too can show lighter arrows going deeper than heavy arrows but there were many differences, where my example was controlled to show specifically that a slick body in the said example is "better" than an increase in foc.
Here is 486 plowing through two targets at around 271fps. This is not my first rodeo, you are going to have to provide some evidence if you want to claim contrary to what i have experienced. Remember 300fps and 400 grains did not get near what this did in two. Also a different shaft size, tapered insert...
Im not worked up. Why would you think that? Are you for some reason upset?
 

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4fletch

4fletch

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Foam is not a great medium for testing arrow penetration in my experience because different shaft materials/finishes can have a pretty wide range which can effect penetration. Ballistic gelatin would be a much better medium.
That is why foam. Different shafts will have a wide range of friction going through things like bison hide. Or passing from hide to intestine across bone... I think gel is good for showing cutting properties but idk about comparing the rest of the arrow. In an ideal world we could use layers that are constant we can control and replicate to show the effect of passing from one to another. Im not sure it has to be realistic. It could be carpet, foam, rubber, plastic in layers. Something of the sort. The issue being FMJs dislike being rammed into things and dont always come back straight.
 

Trial153

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The thing that confuses me about performing testing like this is it has no real application to carry over to any application out side the test. Unless the goal was to apply the results that specific target with those specific arrows I don't see where any conclusions can be drawn.
 
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4fletch

4fletch

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The thing that confuses me about performing testing like this is it has no real application to carry over to any application out side the test. Unless the goal was to apply the results that specific target with those specific arrows I don't see where any conclusions can be drawn.
Reduction in shaft friction is a bigger factor in pen depth than an increase in FOC when the diameter and weight of the arrows remains constant in a medium that is constant.
So i believe if you were building an arrow and had a specific velocity and weight in mind you could apply this and use FMJs over the axis even though the axis has a higher FOC as the slick body of the fmj....yada.
Frankly on deer most arrows will blow through, but in an angled shot? Perhaps one where there is thick hide game? Then the body of the arrow may be under increased contact and the difference may be shaft friction.
I knew this would ruffle feathers because FOC and heavy was the in thing. When i started velocity was king. Same kid of dudes swearing that the lightest stick traveling the fastest was the be all end all.
the point is, Everything matters. Its all give and take. And this even though its not liked is an example of friction reduction being more important than higher foc, In this case.
 

Trial153

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Reduction in shaft friction is a bigger factor in pen depth than an increase in FOC when the diameter and weight of the arrows remains constant in a medium that is constant.
So i believe if you were building an arrow and had a specific velocity and weight in mind you could apply this and use FMJs over the axis even though the axis has a higher FOC as the slick body of the fmj....yada.
Frankly on deer most arrows will blow through, but in an angled shot? Perhaps one where there is thick hide game? Then the body of the arrow may be under increased contact and the difference may be shaft friction.
I knew this would ruffle feathers because FOC and heavy was the in thing. When i started velocity was king. Same kid of dudes swearing that the lightest stick traveling the fastest was the be all end all.
the point is, Everything matters. Its all give and take. And this even though its not liked is an example of friction reduction being more important than higher foc, In this case.

Friction from both shaft material and diameter following a broadhead though an animal? You really feel like you can quantify that in a foam block? Sorry buddy, appreciate the effort but the test is way off base. You have so many variables and possible outliers that quite frankly it’s silly to even hint at any type of conclusive results.
 
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