Powder burn rate question

[savagedasher]

FWIW Hodgdon published data (24-in barrel, MAX for 125-gr bullet - close enough to 123 for the purpose):

H4831: 48.0C 2862 fps
H4350: 44.3 2867 fps

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Close enough for the average shooter.
I don't load that way but that is me.
Larry

 

[kvd]

Hodgdon has an extensive list of 150 powders ranked from fastest to slowest.

Does anyone know the methodology used to create such a list?

Ken

 

[Brians356]

Hodgdon has an extensive list of 150 powders ranked from fastest to slowest.

Does anyone know the methodology used to create such a list?

Ken

Here's one article with more information than most sources (but not much).

http://www.chuckhawks.com/powder_burn_rate.htm

 

[Racecamaro]

I am Posting this for SavageDasher- He said This is a Slow motion pix of what everyone is using in AR Type Rifles

 

[savagedasher]

I am Posting this for SavageDasher- He said This is a Slow motion pix of what everyone is using in AR Type Rifles

Thanks Dave
This is a powder that was recomended for a ar . Burn percentage is in the mid 80 . Larry

 

[Brians356]

Thanks Dave
This is a powder that was recomended for a ar . Burn percentage is in the mid 80 . Larry

Burn percentage might be 80%. But that muzzle flash is not burning powder. All the powder that will be burnt has been burnt by very shortly after pressure peaks, and that happens within a relatively few inches. Muzzle flash is hot flammable gasses igniting when oxygen outside the bore is introduced, not burning powder. If you look at the photo, would burning powder kernels look like that?
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[XTR]

To the OP, burn rate isn't the only factor, but it is the one we can find reasonable measures and listings that we can use in decision making.

Try to visualize a graph of the pressure curve over time. It goes up fast and drops off.

The concept is that a "fast" powder makes a sudden sharp peak to max when it burns and then the pressure drops off as the bullet moves down the barrel and enlarges the space behind it.

On the other hand a "slower" powder will have slower rise to peak pressure allowing/requiring the use of more powder to achieve max pressure in the process causing the pressure behind the bullet to be higher for longer thus getting more velocity.