purpose of cotton in brass after powder

He might have been using a blackpowder substitute and needed to use the cotton filler to keep the powder at the base of the case near the flash hole.
 
Without much in the way of details in your OP, I was speculating then and will do so again. He may have shooting reduced loads and and much like my original response regarding BP, he may have been using the filler to keep the powder up near the flash hole for more consistent ignition. IMR 4064 is the first powder that comes to my mind that would be packaged in a light blue and white can and suitable for the .243 though I won't speculate about it's suitability in using it in reduced loads that would necessitate using a filler. More info about the powder would be helpful.
BD
 
i use filler in many cartridges.
when i load my 405 winchester with pistol bullets, the powder fills only about 25% of the case. the pillow stuffing keeps the powder near the flash hole.
 
It prevents flash over, an uncontrolled burn of powder at accelerated rate, which can cause excessive pressure.

If running a powder that doesn't sufficiently fill the case, and the primer fires across the top of the powder, all of the powder ignites at once. While one assumes the powder all goes boom at one time when you squeeze the trigger, it is actually a controlled burn process. The cotton is used to hold the powder at the bottom of the case to prevent said flash over.
 
I'm not saying you are totally incorrect, but I'd say a more accurate answer would be to achieve more consistent pressures/velocities/less standard deviation.

When a primer goes off, I don't think the powder just lies there in the case.

Plus, what if the powder was up by the bullet to begin with, with space between it and the primer? Or by flash hole with dead space between it and bullet?

I have read studies of reduced loads where pressure spikes from a 40% case fill will produce the same amount of pressure as something like a 60% case fill. However, I do not recall them ever spiking beyond the safe operating limits of the firearm. But that's a bit more in-depth than I care to get here
grin.gif


S.E.E. is the main concern of reduced loads, and what needs to be avoided.........
 
I was thinking also about how race cars have fuel cells with foam in them to keep gas from splashing around. I would think it would not be as explosive with the foam as reg tank with fumes in it. The foam taking up space so wouldnt get a good fuel to air mixture causeing a greater explosion.
 
Originally Posted By: Rocky1It prevents flash over, an uncontrolled burn of powder at accelerated rate, which can cause excessive pressure.

If running a powder that doesn't sufficiently fill the case, and the primer fires across the top of the powder, all of the powder ignites at once. While one assumes the powder all goes boom at one time when you squeeze the trigger, it is actually a controlled burn process. The cotton is used to hold the powder at the bottom of the case to prevent said flash over.

Not true... this is so silly that I am tempted to say "You can't make this stuff up.", but obviously someone did.

There is no such thing as "Flash-over". This is another reloading wive's tale. The primer ignites ALL the powder at once. The granules control their own burn rate. That's why they have burn rates.


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Originally Posted By: Rocky1It prevents flash over, an uncontrolled burn of powder at accelerated rate, which can cause excessive pressure.

If running a powder that doesn't sufficiently fill the case, and the primer fires across the top of the powder, all of the powder ignites at once. While one assumes the powder all goes boom at one time when you squeeze the trigger, it is actually a controlled burn process. The cotton is used to hold the powder at the bottom of the case to prevent said flash over.
Quite correct. When I used to reload, if I used a powder that didnt fill the case at least 2/3 rds I would always use a filler. Best stuff I found was some furniture filler that was very fine almost like cotton wool, but burnt very fast and completely leaving no fouling in the barrel or case
 
Originally Posted By: Raymond BlakerOriginally Posted By: Rocky1It prevents flash over, an uncontrolled burn of powder at accelerated rate, which can cause excessive pressure.

If running a powder that doesn't sufficiently fill the case, and the primer fires across the top of the powder, all of the powder ignites at once. While one assumes the powder all goes boom at one time when you squeeze the trigger, it is actually a controlled burn process. The cotton is used to hold the powder at the bottom of the case to prevent said flash over.
Quite correct. When I used to reload, if I used a powder that didnt fill the case at least 2/3 rds I would always use a filler. Best stuff I found was some furniture filler that was very fine almost like cotton wool, but burnt very fast and completely leaving no fouling in the barrel or case

That you used a filler does not validate the wive's tale of "flash-over"... which cannot happen, do to the way smokeless powder burns.


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There's a neat powder, something like "puff-alon", that's a lubricant that is sold as a case filler. Their tests are pretty conclusive that accuracy improves. Compressed loads have always shown better accuracy than loads with air spaces in them.
 
I'm just getting into this reloading game, and I certainly ain't no expert but, wives tale or no, what I do know is, The Hornady Reloading Manual, 8th Edition, Page 74, item 11 states...

Quote:Don't use reduced loads of slow burning powders. Reduced loads can cause both high pressures and unpredictable results. Don't test your luck on the subject.


There's also a very informative debate on the 1911 forum concerning reduced loads and this phenomenon, whether it be Flashover or Secondary Explosive Effect, whether it exists at all, or whether it be wives tale. And, while several very knowledgeable folks there suggest, much like some of you guys, that it doesn't exist, several folks there do reiterate the warning of reduced loads of slow burning powders in rifles.

And, if you Google " Reloading Case Filler ", you will find the same argument all over the internet. Which... that's the internet where opinions are like, well you know.

I do know that I have found what appear to be credible arguments on both sides of this one, and then when you top that with the above cited reference in the "Don't" do this list, in the Hornady Manual, it tends to lend some credence.

The question was asked why folks pack their loads with cotton, and whether Flash Over exists or not, a large part of the reason they pack them is to prevent Flash Over. And, to keep all the powder down by the flash hole.



 
Originally Posted By: Bigdog2There's a neat powder, something like "puff-alon", that's a lubricant that is sold as a case filler. Their tests are pretty conclusive that accuracy improves. Compressed loads have always shown better accuracy than loads with air spaces in them.

Not true. Many top accuracy loads leave air space in the case.


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A packed case would have a different burn rate than non packed case correct? Lets try it this way. Take a pvc pipe with a cap on it and stand up right on table. Fill a 1/4 full with powder. Now lay that pipe down and spread that powder out long ways. Now you are going to have a faster burn rate because of the air and the ability for the flame to travel over and ignitiing more gr. faster than if it was packed.

The powder will burn up faster spread out more than if it was compressed. Take a handful of sawdust and place it neatly in the fire,then take that same handful and throw it in the fire. The hand thrown sawdust is going to burn right now.
 
Originally Posted By: predyotevarmint
A packed case would have a different burn rate than non packed case correct? Lets try it this way. Take a pvc pipe with a cap on it and stand up right on table. Fill a 1/4 full with powder. Now lay that pipe down and spread that powder out long ways. Now you are going to have a faster burn rate because of the air and the ability for the flame to travel over and ignitiing more gr. faster than if it was packed.

The powder will burn up faster spread out more than if it was compressed. Take a handful of sawdust and place it neatly in the fire,then take that same handful and throw it in the fire. The hand thrown sawdust is going to burn right now.

WHAT???

You gotta be kidding. Is this a 4th grade science project? You get an "F".


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Originally Posted By: CatShooterOriginally Posted By: predyotevarmint
A packed case would have a different burn rate than non packed case correct? Lets try it this way. Take a pvc pipe with a cap on it and stand up right on table. Fill a 1/4 full with powder. Now lay that pipe down and spread that powder out long ways. Now you are going to have a faster burn rate because of the air and the ability for the flame to travel over and ignitiing more gr. faster than if it was packed.

The powder will burn up faster spread out more than if it was compressed. Take a handful of sawdust and place it neatly in the fire,then take that same handful and throw it in the fire. The hand thrown sawdust is going to burn right now.

WHAT???

You gotta be kidding. Is this a 4th grade science project? You get an "F".


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Just making it easier to understand. The point is still the same. Pressure would be different from the same amount of powder if it was only packed a different way.
 
Originally Posted By: predyotevarmintOriginally Posted By: CatShooterOriginally Posted By: predyotevarmint
A packed case would have a different burn rate than non packed case correct? Lets try it this way. Take a pvc pipe with a cap on it and stand up right on table. Fill a 1/4 full with powder. Now lay that pipe down and spread that powder out long ways. Now you are going to have a faster burn rate because of the air and the ability for the flame to travel over and ignitiing more gr. faster than if it was packed.

The powder will burn up faster spread out more than if it was compressed. Take a handful of sawdust and place it neatly in the fire,then take that same handful and throw it in the fire. The hand thrown sawdust is going to burn right now.

WHAT???

You gotta be kidding. Is this a 4th grade science project? You get an "F".



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Just making it easier to understand. The point is still the same. Pressure would be different from the same amount of powder if it was only packed a different way.

NOT...

You are guessing.... and you are wrong!


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