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Old November 23, 2013, 06:31 AM   #1
simonrichter
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Standard test barrel length for.223 ballistic data

Alas, in most of the ballistic charts for .223, the length of the test barrel is not specified. Which is kind of odd, given that sometimes very detailed information is attached, such as air temperature or the like. Is it maybe that there is some kind of a standard test barrel length that can be assumed in case nothing different is stated?
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Old November 23, 2013, 07:06 AM   #2
Bart B.
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Check out page 153 in

http://www.saami.org/specifications_...wnload/206.pdf

That's the industry standard but not always used. If your barrel is shorter as well as having larger bore, groove and chamber dimensions, it'll shoot the same load a bit slower in velocity and with less pressure. Page 41 shows the dimention tolerances. Page 94 starts explaining standard test procedures that may or may not be uses.
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Last edited by Bart B.; November 23, 2013 at 07:14 AM.
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Old November 23, 2013, 07:36 AM   #3
simonrichter
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cool, 24" it seems to be, then.

thx
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Old November 23, 2013, 09:16 AM   #4
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If the ballistics data is based on muzzle velocity (and a bunch of other factors), what difference does it make what barrel length is being used. Barrel length won't be a factor in the ballistics calculation.
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Old November 23, 2013, 10:03 AM   #5
Bart B.
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Hodgdon lists barrel lengths for their load data. With a load's data shown, click on [Print] then move the "Print" window aside and it uncovers a chart with the barrel length and other component stuff listed.
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Old November 23, 2013, 10:50 AM   #6
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Quote:
If the ballistics data is based on muzzle velocity (and a bunch of other factors), what difference does it make what barrel length is being used. Barrel length won't be a factor in the ballistics calculation.
This is the answer. Any ballistics chart will be an approximation anyway, because it is very unlikely that your rifle and environmental variables match theirs.

For best results, you need to chrono you loads, then use something like JBM Ballistics, and enter your actual variables, MV, sight height, temp, altitude, etc.

And the best ballistic calculator in the world is still not a substitute for actually shooting the rifle, and seeing where it shoots at various ranges in the real world.
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Old November 23, 2013, 03:22 PM   #7
simonrichter
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Quote:
If the ballistics data is based on muzzle velocity (and a bunch of other factors), what difference does it make what barrel length is being used. Barrel length won't be a factor in the ballistics calculation.

eh, much difference? When I know fps (and thus, ft lbs) of a certain round, I also need to know whether these were achieved out of a 16" or a 24" barrel... Otherwise it tells me nothing about the performance of the round out of my certain gun.
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Old November 23, 2013, 03:39 PM   #8
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"...much difference? When I know fps (and thus, ft lbs) of a certain round, I also need to know whether these were achieved out of a 16" or a 24" barrel... Otherwise it tells me nothing about the performance of the round out of my certain gun."

Sadly, what the loading data was developed in is nearly irrelivant so far as being meaningful for your certain rifle. IF you want to know what speed a load is doing for you, run it over a chronograph. Anything else is no more than a guess, and a poor one at that.
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Old November 25, 2013, 11:28 PM   #9
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Quote:
Sadly, what the loading data was developed in is nearly irrelevant so far as being meaningful for your certain rifle. IF you want to know what speed a load is doing for you, run it over a chronograph. Anything else is no more than a guess, and a poor one at that.
Cool so when I'm doing load development for my 16" 223 and the books max load shows 3000fps . But though my chrono and my 16" barrel I'm only getting 2750fps with no pressure signs . If the length of the test barrel has NO relevance at all . That must mean I can keep loading heavier and heavier charges till I get close to the books muzzle velocity as long as there's NO pressure signs . RIGHT ? . Thanks for the safe info , this should help most of us new loaders and everybody around us at the range while testing
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Old November 26, 2013, 12:08 AM   #10
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Metal God,

I think you didn't understand wncchester. His point was that even the ballistic data on the side of commercial ammo is only a best guess for your particular rifle, if you don't verify it with a chronograph (or by drop calculations at different ranges is another way to do it with good enough precision).

Published load data is always "do not exceed." Once you hit max charge, do not go over. If you aren't getting the velocity listed in the book, so what?

The guy with the 16" barrel will get less velocity (but he won't know how much until he runs it over a chronograph) and the guy with a 28" barrel might get a bit more (but he won't know until he runs it over a chronograph).

I appreciate your sarcasm, but I don't joke about exceeding max loads.

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Old November 26, 2013, 01:01 AM   #11
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Oh I get it , and I thought is was very important that one guy out there reading this thread does too . What length barrel the load data used and or what ever was tested matters . It all matters !

I knew I was going to get a response really quick but your right , I should have explained what I was really meaning after my sarcasm to make sure that one guy understood . I should not have left that hanging out there .

For that I'm sorry

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Old November 27, 2013, 10:14 AM   #12
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Metal God,

Yes everything matters, but I think it should also be noted that even barrels of the same length can have different velocities shooting the same ammo due to all sorts of differences. And no one will know until you chrono the ammo through that rifle.

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