Re: Powder Burn Rate Chart... NEW
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:
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 by LouBoyd; 06-09-2011 at 10:31 AM.