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Powder Burn Rate Chart... NEW
- Thread starter Sendero_Man
- Start date
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358sta
Well-Known Member
Looks to be pretty much up to date as it has Superformance and Leverevolution listed but not Alliant's new RL-50 which has been out for over a year now.
LouBoyd
Well-Known Member
The problem with a chart like that is that burn rate is not a single parameter which defines the characteristcs of a firearms propellant..
In the computer program "Quickload" there are eight coefficients used to define each powder.
The coefficients of each powder are determined by laboratory burn tests on samples of each powder.
The parameters are:
bulk density
solid density
heat of explosion
ratio of specific heats
Ba,factor b, limit z1, and pro/degressivity coefficient.
The last four describe the "burn rate" which certainly isn't defineable just by it's posiiton on a one dimensional chart, yet less by it's posiiton on a list.
Even getting the eight parameters above optimally correct deoesn't completely define a powder's characteristics, but it does give a decent prediction of the pressure curve and energy transferred to a bullet in the conditions of typical firearms chambers and barrels.
Because burn rates are non-linear the speed at whch powders burn change with the conditions under which they are burned. Burn rate charts give no indication of what those conditions are. You frequently see charts which change the order of various powders. That's doesn't mean the powders have changed or that one chart is in errror, rather that the condiitions of the tests aren't the same.
Hogdon's (and similar) burn rate chart may be of some use, but in no way does it mean that two powders which are adjacent on the chart are interchangable with only a small change of charge weight.. To think so is asking for disaster.
Would you sort a room full of people by their height and think you had a good representation of their capabilities? It would have some correlation. The babies would be a one end and adults at the other, and their strength would have some correlation to the chart. maybe as much as with the powder burn rate charts.
In the computer program "Quickload" there are eight coefficients used to define each powder.
The coefficients of each powder are determined by laboratory burn tests on samples of each powder.
The parameters are:
bulk density
solid density
heat of explosion
ratio of specific heats
Ba,factor b, limit z1, and pro/degressivity coefficient.
The last four describe the "burn rate" which certainly isn't defineable just by it's posiiton on a one dimensional chart, yet less by it's posiiton on a list.
Even getting the eight parameters above optimally correct deoesn't completely define a powder's characteristics, but it does give a decent prediction of the pressure curve and energy transferred to a bullet in the conditions of typical firearms chambers and barrels.
Because burn rates are non-linear the speed at whch powders burn change with the conditions under which they are burned. Burn rate charts give no indication of what those conditions are. You frequently see charts which change the order of various powders. That's doesn't mean the powders have changed or that one chart is in errror, rather that the condiitions of the tests aren't the same.
Hogdon's (and similar) burn rate chart may be of some use, but in no way does it mean that two powders which are adjacent on the chart are interchangable with only a small change of charge weight.. To think so is asking for disaster.
Would you sort a room full of people by their height and think you had a good representation of their capabilities? It would have some correlation. The babies would be a one end and adults at the other, and their strength would have some correlation to the chart. maybe as much as with the powder burn rate charts.
Last edited:
Kevin Thomas
Well-Known Member
Excellent commentary and good analogies by Lou. Heed the man's advice.
Sendero_Man
Well-Known Member
Posted it just an FYI for anyone looking for new/updated chart with some of the latest powders that have come out...
nothing more, nothing less.
nothing more, nothing less.
mikebob
Well-Known Member
Thanks for the link I have been looking for a new list.
mikebob
Well-Known Member
We do not use list for powder charges, we use list to find a powder a little slower or faster than what we are using. Then go to manual and find min and max charge weights, start low and work up. I have Quickload myself and it is not all that accurate either. You can not punch numbers in quickload and expect them to be accurate either.
The problem with a chart like that is that burn rate is not a single parameter which defines the characteristcs of a firearms propellant..
In the computer program "Quickload" there are eight coefficients used to define each powder.
The coefficients of each powder are determined by laboratory burn tests on samples of each powder.
The parameters are:
bulk density
solid density
heat of explosion
ratio of specific heats
Ba,factor b, limit z1, and pro/degressivity coefficient.
The last four describe the "burn rate" which certainly isn't defineable just by it's posiiton on a one dimensional chart, yet less by it's posiiton on a list.
Even getting the eight parameters above optimally correct deoesn't completely define a powder's characteristics, but it does give a decent prediction of the pressure curve and energy transferred to a bullet in the conditions of typical firearms chambers and barrels.
Because burn rates are non-linear the speed at whch powders burn change with the conditions under which they are burned. Burn rate charts give no indication of what those conditions are. You frequently see charts which change the order of various powders. That's doesn't mean the powders have changed or that one chart is in errror, rather that the condiitions of the tests aren't the same.
Hogdon's (and similar) burn rate chart may be of some use, but in no way does it mean that two powders which are adjacent on the chart are interchangable with only a small change of charge weight.. To think so is asking for disaster.
Would you sort a room full of people by their height and think you had a good representation of their capabilities? It would have some correlation. The babies would be a one end and adults at the other, and their strength would have some correlation to the chart. maybe as much as with the powder burn rate charts.
rscott5028
Well-Known Member
Given Lou's comments...
Would it be safe to compare Superformance which is adjacent to H4831sc to H4831sc load data and lacking data for a given cartridge, start a conservative load workup using the minimal charge weight for H4831sc?
Or, are the charge weight and burn rate completely independent?
I suspect they are completely independent as I see load data for a random cartridge that shows 49.0g as a starter load for H4831 and 43.2g for N160 both of which are adjacent in the table. As such, the starter load for H4831sc is well above the max load for N160.
I like the list for what it is. But, it's not load data.
-- richard
Would it be safe to compare Superformance which is adjacent to H4831sc to H4831sc load data and lacking data for a given cartridge, start a conservative load workup using the minimal charge weight for H4831sc?
Or, are the charge weight and burn rate completely independent?
I suspect they are completely independent as I see load data for a random cartridge that shows 49.0g as a starter load for H4831 and 43.2g for N160 both of which are adjacent in the table. As such, the starter load for H4831sc is well above the max load for N160.
I like the list for what it is. But, it's not load data.
-- richard
Kevin Thomas
Well-Known Member
Given Lou's comments...
Would it be safe to compare Superformance which is adjacent to H4831sc to H4831sc load data and lacking data for a given cartridge, start a conservative load workup using the minimal charge weight for H4831sc?
Or, are the charge weight and burn rate completely independent?
I suspect they are completely independent as I see load data for a random cartridge that shows 49.0g as a starter load for H4831 and 43.2g for N160 both of which are adjacent in the table. As such, the starter load for H4831sc is well above the max load for N160.
I like the list for what it is. But, it's not load data.
-- richard
Charge rate and burn rate are completely independant issues. Burn rate charts are useful tools for comparing powders when trying to decide whether one will be useful in a given application, but as has been stated, you still need some reference source to establish a load. That's where lab developed, empirically tested data from the manufacturers comes in. The analogy here between H4831 and our own N160 is a good one. Very similar in burning rate, but substantially different in many other regards.
