Greater distance = penetration?

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JPH
 
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Greater distance = penetration?

Postby JPH » Sun Aug 31, 2008 7:51 am

I have been bow hunting for 13 years, but I've never been a "techie". I am always confused as to why arrows do what they do.
 
I was shooting my new carbon arrows last night, into a compressed foam layer target. I noticed that the shafts got about 6" of greater penetration at 20-35 yds. than at 10-15 yds. What gives?

Highlander Archery
 
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RE: Greater distance = penetration?

Postby Highlander Archery » Sun Aug 31, 2008 9:17 am

The paradox of your arrow may be exaggerated at 10 and 15 yards as opposed to 20 or 30, this is usually an indicator of a spine mismatch or improper tuning. BUT shooting into an ethafoam target is a poor way to gauge penetration, soft spots in the foam from mfg or frequent shooting can affect the distance your arrow passes through a target.

If you paper tune, after obtaining a bullet hole group tune your arrows at ranges from 10 to 40 or 50 yds, if your groups are erratic (very open at 10 yds, tight at 40 or vise versa) you need to make micro adjustments to your rest and or nock point. Groups should open incrementally as range increases, 1 inch at 20 or less, 2 inches at 30, 3 inches at 40, 4 inches at 50. Of course this will be affected by your shooting form and is not a set in stone gauge. If you hold 3 inch groups at 20 yds, expansion should be at a similar ratio.

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JPH
 
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RE: Greater distance = penetration?

Postby JPH » Sun Aug 31, 2008 9:30 am

Thanks for the reply. As I said, I'm no technical wizard when it comes to archery, so most of it was over my head. But I did get the central message. It's most likely a fluke.
 
I shoot with acceptable accuracy out to 35 yds or so. Given my limitations in time and budget, I'll call it good.

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RE: Greater distance = penetration?

Postby Highlander Archery » Sun Aug 31, 2008 9:35 am

ORIGINAL: JPH

Thanks for the reply. As I said, I'm no technical wizard when it comes to archery, so most of it was over my head. But I did get the central message. It's most likely a fluke.

I shoot with acceptable accuracy out to 35 yds or so. Given my limitations in time and budget, I'll call it good.


That's what I figured considering 13 yrs experience, without standing next to you while you shoot it is hard to give anything but a general answer in these situations.

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trapperDave
 
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RE: Greater distance = penetration?

Postby trapperDave » Sun Aug 31, 2008 1:53 pm

wrong arrow spine or poor bow tuning. Your flething is fighting to get the arrow straight.
"Democracy is a lamb and two wolves voting on what to have for lunch; Liberty is a well armed lamb contesting the vote." Ben Franklin

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mag30079
 
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RE: Greater distance = penetration?

Postby mag30079 » Mon Sep 01, 2008 2:22 am

JPH,

you just switched from alumimium to carbon, your new carbon are lighter. The lighter the arrow the more dynamic spine. It now takes twice as long for the arrow in flight to recover, meaning the kinetic energy is still moving down the arrow shaft and may peak closer to 20 vs 10. What type of fletchings are you using?
 
As you said your shooting fine out to 35yrds. I wouldn't worry to much about it. As for the technical wizard, that doesn't compair to the deer that you've taged.

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JPH
 
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RE: Greater distance = penetration?

Postby JPH » Mon Sep 01, 2008 3:53 am

ORIGINAL: mag30079

 The lighter the arrow the more dynamic spine. It now takes twice as long for the arrow in flight to recover, meaning the kinetic energy is still moving down the arrow shaft and may peak closer to 20 vs 10. What type of fletchings are you using?



Hmm, I never changed my arrow length when I went to a wisker bisket a few years ago. It kind of works like an overdraw. When I had my carbons cut, I stayed with that length. At full draw, my broad head sits about 1.5"-2" in front of my rest. I wonder if a shorter arrow might clean up the flight a bit?

But how do I do that now that they are cut and the inserts are fixed? And would it require a lot of adjustment in my sights, etc.?
 
Secondly, I have gone from 4" vanes on my old 2117, to the 2" vanes on the carbons. I suppose that may play some part as well, but I don't want to change them. They seem to be a lot more durable. Plus, I figure that given my lousy form, the less contact with my bisket - the better!

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RE: Greater distance = penetration?

Postby Highlander Archery » Mon Sep 01, 2008 6:56 am

ORIGINAL: JPH

ORIGINAL: mag30079

The lighter the arrow the more dynamic spine. It now takes twice as long for the arrow in flight to recover, meaning the kinetic energy is still moving down the arrow shaft and may peak closer to 20 vs 10. What type of fletchings are you using?



Hmm, I never changed my arrow length when I went to a wisker bisket a few years ago. It kind of works like an overdraw. When I had my carbons cut, I stayed with that length. At full draw, my broad head sits about 1.5"-2" in front of my rest. I wonder if a shorter arrow might clean up the flight a bit?

But how do I do that now that they are cut and the inserts are fixed? And would it require a lot of adjustment in my sights, etc.?

Secondly, I have gone from 4" vanes on my old 2117, to the 2" vanes on the carbons. I suppose that may play some part as well, but I don't want to change them. They seem to be a lot more durable. Plus, I figure that given my lousy form, the less contact with my bisket - the better!


If you bought the properly spined arrow to begin with, changing the length is not critical so do'nt worry about that. The shorter vanes are making the dynamic spine of your arrow stiffer though(Flex in motion).

Assuming proper spine exists, adjust rest towards the riser 1/32" to 1/16".


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