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Understanding FOC?

Get lighter carbon arrows and replace the missing weight from ditching the fmjs in the point of the arrow. Still get the same or similar TAW but a higher FOC. Would only take about 100gr added to point weight with carbon shaft to do so. That’d get you in the ball park.


Sent from parts unknown
 
drew13 said:
Agreed that poor arrow flight robs penetration. But would be interested to know his buddy’s arrow setup and FOC vs his FMJ‘s at 7.1% FOC....

7.1% vs 15+% would be a big difference! It definitely would explain some of the differences they’re seeing in penetration.
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I txted him. The difference is he's shooting 125gr heads with heavier inserts. My bad.

As for arrow flight, I'm fresh outta the shop all paper tuned and timed. She's mint. Just a weight difference is all.
 
Hunter260 said:
Let’s take 2 hypothetical setups to compare them, both 500 grain arrows total weight with head. Arrow A has a 50 grain broadhead and the arrow B a 250 grain broadhead, (not really realistic but go with me). A has 10% weight in broadhead and 90% in shaft. B is split 50% head and 50% shaft. We know that when you hit one end of your arrow shaft really hard the whole arrow flexes. This happens at shot and at impact. So, when you hit the deer with arrow A and the broadhead punctures the skin, you’ve got 10% of the weight pulling the arrow straight through the deer, while 90% of the weight is pushing into a deer and wasting energy flexing your arrow. I think you see where this is going... more head weight is less weight that is being wasted pushing your shaft and bending and an overall more efficient impact.
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Well said
 
SnakeEater said:
Get lighter carbon arrows and replace the missing weight from ditching the fmjs in the point of the arrow. Still get the same or similar TAW but a higher FOC. Would only take about 100gr added to point weight with carbon shaft to do so. That’d get you in the ball park.


Sent from parts unknown
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That is the way to get high foc. I can see that you dont want to do it now @HuntNorthEast. But consider it for next year.
 
heretic said:
DISCLAIMER: This is merely my hypothesis, we'd need an actual thorough scientific study to validate this.

Your penetration is maximized when 100% of your inertial mass is directly inline with the path of travel. Critters move, deflections happen. Higher FOC moves the fulcrum closer to the point of initial impact and helps steer the broadhead past those critical few miliseconds of initial penetration. The closer your fulcrum is to the point of impact, the harder it is for your arrow to be deflected off the path of travel (i.e. maximizing your penetration).

As a thought experiment, open a door and then try to close it by pushing it close to the handle. Pretty easy right? Now try closing it by pushing as close as you can to the hinges, a bit harder? Same mechanics apply to FOC.
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I feel so much smarter having read this. Thank you.
 
SnakeEater said:
Dr. Ashby recommends 19% FOC. You can go the the Ashby foundation web site and read his findings, there is a lot of information to be shared on there regarding FOC and arrow construction.

www.ashbybowhunting.org

Ashby Bowhunting Foundation

www.ashbybowhunting.org www.ashbybowhunting.org


Sent from parts unknown
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Yeah, go check out Ashbybowhunting.org
Dr Ed Ashby knows probably more about arrow lethality than anyone. Complete penetration is the key and high FOC is just one ingredient to increased penetration. Dr Ed has a list of criteria for maximum penetration. He has a butt load of reports and videos on arrows and broadheads.
The Grizzlystik website also has all his reports. Check out what the weight of just one paper clip on the nock end of an arrow does to FOC.
Btw, the Grizzlystik Momentum arrows ( made by Victory) are a tapered shaft, which produces an increase of FOC by 5% due to the taper.
 
Not sure if many of you remember who he is but the ol timer Monte Browning did shoot heavy ol fish arrows that weighed 1000 grains or more for EVERYTHING he hunted from rabbits to African game with his heavy draw longbows using 2 blade cut in contact heads and he was quite successful at it
 
SnakeEater said:
Get lighter carbon arrows and replace the missing weight from ditching the fmjs in the point of the arrow. Still get the same or similar TAW but a higher FOC. Would only take about 100gr added to point weight with carbon shaft to do so. That’d get you in the ball park.


Sent from parts unknown
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I can be around 15.1% just by switching to a 125gr head and 100gr inserts. Arrows will kill deer as is for this season. Next season I will up the head and inserts and 15.1% should be more than enough! :grimacing:
 
On the asby foundation youtube it's Dr. ed talking about the factors to make a good arrow. He has a way of communicating the ideas effectively in about 4-6 minutes using simple examples.

I've recently heard the difference between a heavy arrow and light arrow as being similar to being hit in the head with a ping-pong ball versus a softball. FOC adds weight, usually, and causes the arrow to be pulled through tissue is my understanding.
 
I'd like to hear some experiences with the amount of penetration guys get when they hit the heaviest bone on the off side shoulder.
We all know that the 2nd best shot angle is the slightly quartering away angle. That means we are actually aiming so our arrow is gonna exit just about at the heaviest bone on the far side, especially if the far leg is back. The odds of getting an exit wound for a lot of us go way down when we hit that far shoulder or the joint of the far leg bone. It might be a great shot, totally lethal. But without an exit wound, will there be an adequate blood trail?
Personally, my reason for wanting a heavy arrow, high FOC, and a bomb-proof broad head is so I can punch thru the far shoulder or leg joint. Gotta have 2 holes.
 
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Allegheny Tom said:
I'd like to hear some experiences with the amount of penetration guys get when they hit the heaviest bone on the off side shoulder.
We all know that the 2nd best shot angle is the slightly quartering away angle. That means we are actually aiming so our arrow is gonna exit just about at the heaviest bone on the far side, especially if the far leg is back. The odds of getting an exit wound for a lot of us go way down when we hit that far shoulder or the joint of the far leg bone. It might be a great shot, totally lethal. But without an exit wound, will there be an adequate blood trail?
Personally, my reason for wanting a heavy arrow, high FOC, and a bomb-proof broad head is so I can punch thru the far shoulder or leg joint. Gotta have 2 holes.
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This is the exit of a doe. I tend to hit a little forward. She dropped like a rock.broke both shoulders.75# draw. 475 grain arrow. Ram at broad head.KIMG0257.jpg

Sent from my KYOCERA-E6820 using Tapatalk
 
Allegheny Tom said:
I'd like to hear some experiences with the amount of penetration guys get when they hit the heaviest bone on the off side shoulder.
We all know that the 2nd best shot angle is the slightly quartering away angle. That means we are actually aiming so our arrow is gonna exit just about at the heaviest bone on the far side, especially if the far leg is back. The odds of getting an exit wound for a lot of us go way down when we hit that far shoulder or the joint of the far leg bone. It might be a great shot, totally lethal. But without an exit wound, will there be an adequate blood trail?
Personally, my reason for wanting a heavy arrow, high FOC, and a bomb-proof broad head is so I can punch thru the far shoulder or leg joint. Gotta have 2 holes.
Click to expand...
I will let you know after this season...
I shot a doe with my old bow and setup where i hit the offside leg bone and broke it. The arrow left two holes but she broke it into three pieces when she ran. This years setup should do better.
 
Allegheny Tom said:
I'd like to hear some experiences with the amount of penetration guys get when they hit the heaviest bone on the off side shoulder.
We all know that the 2nd best shot angle is the slightly quartering away angle. That means we are actually aiming so our arrow is gonna exit just about at the heaviest bone on the far side, especially if the far leg is back. The odds of getting an exit wound for a lot of us go way down when we hit that far shoulder or the joint of the far leg bone. It might be a great shot, totally lethal. But without an exit wound, will there be an adequate blood trail?
Personally, my reason for wanting a heavy arrow, high FOC, and a bomb-proof broad head is so I can punch thru the far shoulder or leg joint. Gotta have 2 holes.
Click to expand...
Using at 125 magnus 2 blade and 125 grain insert inside a easton arrow, I purposely shot a doe in the shoulder at 21 yards. The arrow completely passed thru both shoulders and buried up 4" in the dirt. The tip of the bh was slightly bent but the arrow and everything else was still in good shape. I managed to straighten the bh out and still use it. Oh, the deer never took a step, drt (dead right there)
 
https://anchor.fm/lethalpodcast/epi...den---The-Physics-of-Arrow-Penetration-efj40g

I think this is the podcast where he relates some conversations with Ashby, who apparently has changed his mind a bit due to modern fast compounds. Bill feels that it is a continuem (sp?) rather than some magic transition that happens over 19%. Warning-the Lethal hosts are not fans of FMJ arrows. Not sure if it comes up in this podcast, but it often does.

John
 
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