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Old November 20, 2007, 10:13 AM   #1
lastchancebaby
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Powder chemistry? Does anyone know why some are clean & some dirty?

Hi,
Moreover, how does pressure effect burn efficiency? Maybe I am going too far; however, I would like to understand molecular dynamics of powder.
Thanks for any help
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Old November 20, 2007, 11:03 AM   #2
rwilson452
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It's my understanding it's what they use for a moderator and how much graphite they add. With smokeless powder higher temperature and or pressure will ensure a more efficient burn. I have found this especially true in pistol powders. in my .45 a tighter crimp can make a lot of difference.
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Old November 20, 2007, 11:52 AM   #3
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"Explosives Engineering" by Paul W. Cooper

Chapters on Oxidation, Estimating Properties of Explosives, Decompositionm, Basic Thermodynamics, Thermophysics, Thermochemistry, Reaction Temperatures, Closed Vessel Calculations, Shock Wave Creation, Propagation, etc.

Not a simple introductory text, but if you have a decent chemistry and engineering backround it provides a lot of relevent data in a single place.
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Old November 20, 2007, 11:52 AM   #4
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yes, some powders need higher pressures and/or longer barrels and unlock times (semi-auto) to burn well.
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Old November 20, 2007, 12:41 PM   #5
lastchancebaby
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This is the best hobby!!!

Hi,
Reloading is not only fun, but educational!
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Old November 20, 2007, 01:21 PM   #6
Archie
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Essentially...

Powder - and most everything else - burns more fully and therefore cleaner at higher temperatures. In the universe of internal ballistics, temperature and pressure are closely related, so powder burns fully at higher pressures.

Powders like Bullseye and Clays (in handguns) or 3031 and 4227 (in rifles) are 'fast' powders. They raise pressure quickly and burn completely with fairly small amounts of powder. Some folks are surprised to find the 'lighter' loads develop about as much maximum pressure as the 'heavier' loads.

Powders like 2400 and W296 (in handguns) or IMR4831 and H870 (in rifles) are 'slow' powders. They require more resistance, either in the form of heavier bullets or tighter crimps in order to raise pressures to the level they burn uniformly and completely.

Using any powder under it's optimum burn rate will result in more residue. Just like burning acetelyne gas without oxygen will give off a smoky, dim flame.

I have a feeling some of the retardants and such in gunpowder may leave their little bit of residue, but probably not much in the grand scheme. I'm pretty sure none of the powder makers are going to add chemicals to powder to make it dirtier.

Load to the proper pressure levels and residue will be a minimum.
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