Finding the percentage of powder burnt

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Finding the percentage of powder burnt

Post by MeccaOz » 25 Jun 2014, 2:01 pm

Hi gurus, is there anyway to find out how much powder is being burnt in a certain barrel. For example say I'm using AR2208 in my .223 and the barrel has been chopped off and is now 18" long, how would I find out how much powder from my old loads was being wasted, is there a formula or ballistics program I could use ?
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Re: Finding the percentage of powder burnt

Post by Chronos » 25 Jun 2014, 6:38 pm

Easiest way would be load testing and a chronograph. Starting at minimum loads and work up toward maximum until velocities plateau. That's all the powder you can burn in the time the bullets in the barrel

Faster powder may get speeds up too

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Re: Finding the percentage of powder burnt

Post by MeccaOz » 25 Jun 2014, 8:11 pm

I thought that was the way to do it, but after reading some comments somewhere I thought there must be a ballistics program that does it.
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Re: Finding the percentage of powder burnt

Post by Warrigul » 26 Jun 2014, 4:00 pm

MeccaOz wrote:Hi gurus, is there anyway to find out how much powder is being burnt in a certain barrel. For example say I'm using AR2208 in my .223 and the barrel has been chopped off and is now 18" long, how would I find out how much powder from my old loads was being wasted, is there a formula or ballistics program I could use ?


Nope no program is available only trial and error, other than a chronograph the best way is to fire at night, you will get a visual of what is going on.(I know it sounds rough but I did it with a Jungle carbine and the results were surprisingly similar to what the chronoggraph indicated.

Just what I have found:

You still need to load at the same rate as before, there is only minimal efficiency to be gained by short loading to suit.
Heavier pills seem to get going better in short barrels with medium powder (2208 and 174grain projectiles in .303) but lighter pills run better with a faster powder(2206 and 125 grainers in .303).

The pressures don't seem to be any less in a shorter barrel but if you go to a longer twist they seem to reduce slightly.

Suck it and see really, I was still able to shoot successfully at 600yards even with the Jungle carbine, it generally is not as much a reduction in velocity as people think.

Rule of thumb in a .308 is 30fps less per inch removed with the same powder charge, so if you are shooting at 1000yards it may make the difference between staying supersonic or not but at 500 it will just mean a small adjustment for elevation.

The .223 is less sensitive to being docked, simply by the one docking I have done with a .223 barrel which in itself is not proof positive. If you do experiment let us all know the results as I would be very keen to know.
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Re: Finding the percentage of powder burnt

Post by MeccaOz » 26 Jun 2014, 5:27 pm

Thanks Heaps Warrigul, I will let everyone know, when i get the stuff to do it and I certainly will post up the results :)
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Re: Finding the percentage of powder burnt

Post by Klem » 01 Jul 2014, 8:40 am

MeccaOz wrote:Hi gurus, is there anyway to find out how much powder is being burnt in a certain barrel. For example say I'm using AR2208 in my .223 and the barrel has been chopped off and is now 18" long, how would I find out how much powder from my old loads was being wasted, is there a formula or ballistics program I could use ?


When you say wasted, are you having problems with unburned powder and low pressure signs?

Or just asking?
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Re: Finding the percentage of powder burnt

Post by Chronos » 01 Jul 2014, 9:39 am

Klem wrote:
MeccaOz wrote:Hi gurus, is there anyway to find out how much powder is being burnt in a certain barrel. For example say I'm using AR2208 in my .223 and the barrel has been chopped off and is now 18" long, how would I find out how much powder from my old loads was being wasted, is there a formula or ballistics program I could use ?


When you say wasted, are you having problems with unburned powder and low pressure signs?

Or just asking?


I think he meant wasted asin it's it burnedby the time the bullet leaves the barrel and therefor makes no contribution to bullet velocity.

Effectively if you have a chronograph you could fire your load in the short barrel, then reduce the powder charge by a small amount each time until you notice a drop in billet velocity. The difference between the starting load and the load where velocity drops is the amount of powder that's burning after the bullet leaves the barrel or is "wasted"

This may or may not effect accuracy and is one reason most hand loaders chase a load with high load density without excessuve pressure and efficient burn.

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Re: Finding the percentage of powder burnt

Post by MeccaOz » 01 Jul 2014, 10:51 am

Sorry I didnt get back sooner guy's. Pretty much Chronos nailed what I was asking. I do have a shorter than average barrel length, and the load the gun likes is a compressed load. While there is something to be said for a completely full column of powder, I not really a fan of compressed loads. So I was checking to see if there was a program out there that could help me with it, after reading some comments people left on a similar thread.... In case I was missing out on something :lol:
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Re: Finding the percentage of powder burnt

Post by Chronos » 01 Jul 2014, 11:48 am

MeccaOz wrote:I do have a shorter than average barrel length.....


That's ok Meccaoz, I'm told its what you do with it that counts. :lol :

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Re: Finding the percentage of powder burnt

Post by MeccaOz » 01 Jul 2014, 11:52 am

Chronos wrote:
MeccaOz wrote:I do have a shorter than average barrel length.....


That's ok Meccaoz, I'm told its what you do with it that counts. :lol :

Chronos

Bursts Out laughing hahahaha, It would be funny if werent true :?
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Re: Finding the percentage of powder burnt

Post by Klem » 01 Jul 2014, 10:02 pm

MeccaOz wrote:Sorry I didnt get back sooner guy's. Pretty much Chronos nailed what I was asking.


Cool.

Good to hear no low pressure concerns going on then ;)
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