Powder chemistry? Does anyone know why some are clean & some dirty?

lastchancebaby · November 20, 2007, 10:13 AM

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

rwilson452 · November 20, 2007, 11:03 AM

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.

brickeyee · November 20, 2007, 11:52 AM

"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.

45Marlin carbine · November 20, 2007, 11:52 AM

yes, some powders need higher pressures and/or longer barrels and unlock times (semi-auto) to burn well.

lastchancebaby · November 20, 2007, 12:41 PM

Hi,
Reloading is not only fun, but educational!

Archie · November 20, 2007, 01:21 PM

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.

November 20, 2007, 10:13 AM	#1
lastchancebaby Member Join Date: October 29, 2007 Posts: 43	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

November 20, 2007, 12:41 PM	#5
lastchancebaby Member Join Date: October 29, 2007 Posts: 43	This is the best hobby!!! Hi, Reloading is not only fun, but educational!

November 20, 2007, 01:21 PM	#6
Archie Senior Member Join Date: May 26, 2000 Location: Hastings, Nebrasksa - the Hear Posts: 2,209	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. __________________ There ain't no free lunch, except Jesus. Archie Check out updated journal at http://oldmanmontgomery.wordpress.com/

November 20, 2007, 11:03 AM	#2
rwilson452 Senior Member Join Date: June 10, 2004 Location: Tioga co. PA Posts: 2,647	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.

November 20, 2007, 11:52 AM	#3
brickeyee Senior Member Join Date: December 29, 2004 Posts: 3,351	"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.

November 20, 2007, 11:52 AM	#4
45Marlin carbine Junior member Join Date: January 26, 2007 Location: South-Western North Carolina Posts: 1,124	yes, some powders need higher pressures and/or longer barrels and unlock times (semi-auto) to burn well.