LKLive13
Member
I have heard that there is a way to calculate the burn rate to compare the similarities of two powders. Does anyone know how to do this?
Burn rate calculations??
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rcmodel
Member in memoriam
NO, there is no way to mathematically 'calculate' burn rates between different powders.
Your best bet is a burn rate chart in about any reloading manual where all the different powders are ranked numerically from fastest to slowest.
http://www.hodgdon.com/burn-rate.html
But you can't put 100% confidence in that either, because burn rate can change with cartridge case design, case capacity, or operating pressure.
Another way is to open any reloading manual and compare the max charges of each powder used in any caliber/bullet weight combination.
Those using less powder to reach max pressure are faster burning.
rc
Your best bet is a burn rate chart in about any reloading manual where all the different powders are ranked numerically from fastest to slowest.
http://www.hodgdon.com/burn-rate.html
But you can't put 100% confidence in that either, because burn rate can change with cartridge case design, case capacity, or operating pressure.
Another way is to open any reloading manual and compare the max charges of each powder used in any caliber/bullet weight combination.
Those using less powder to reach max pressure are faster burning.
rc
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Kernel
Member
The charts usually list powders from fastest to slowest. But they do not mean any more than that. Powder "B" might be in between powder "A" and "C". That does not mean it is exactly 1/2 way in burn rate. It might be very close to "A", and the jump to "C" could be huge.
rcmodel
Member in memoriam
That too!
And I have yet to see two burn rate charts that even agree with each other all the way through.
rc
And I have yet to see two burn rate charts that even agree with each other all the way through.
rc
ArchAngelCD
Member.
Correct, the charts can tell you which powders are faster or slower than others but not HOW MUCH faster or slower.
Even if we could calculate powder burn rate to a fairly accurate degree, what is your intention with the information? It seems to me that real world testing of a specific powder in a certain contained volume, with a specific weight bullet is a much better model than using mathematical calculations. It seems this is why we have reloading manuals that summarize actual testing of how a powder will react in certain cartridges and conditions. Sometimes you just have to shoot'em.
243winxb
Member
Powder Burn Rates
Design Integrated Technology, Inc (DIT) manufactures the Closed Bomb (Powder Bomb). It is used for determining the quickness and force of a test propellant sample.http://www.ditusa.com/closed_bomb.php
Design Integrated Technology, Inc (DIT) manufactures the Closed Bomb (Powder Bomb). It is used for determining the quickness and force of a test propellant sample.http://www.ditusa.com/closed_bomb.php
OP
OP
LKLive13
Member
I was just curious if there was a way to compare they way two desperate powders react base off the charts listed above. Say if WSF is listed as a documented load but longshot is not, I was wondering if there was a way to "predict" how longshot would work with the knowledge of how WSF works. I understand that you should only use published load data and I was just curious.
Kernel
Member
No, there isn't. There are mathematical techniques which will select a powder, a load weight, and predict a velocity. Those formulas don't always work so well with handguns because the cases are so tiny and the powders so fast.
"Quick Load" is a program you can buy that will do the math. It is very sophisticated and pretty accurate. There is also the old "Powley Computer" that was a kind of slide rule developed in the 1960's and sold mail order for decades. This link explains the math behind the Powley Computer:
http://web.archive.org/web/20041126...allisticsonline.com/ballistics/imrpowder.html
Link to free online Powley Computer (not for handgun cartridges):
http://kwk.us/powley.html
Andrew Leigh
Member
Perhaps the closest you will get is to buy QuickLOAD. It has a probably 100 powders in the data base that are quoted at the manufacturers nominal specification. Now we all know that batches will vary but this would give a very close approximation.
What we then do is to "calibrate" a powder burn rate for a batch. We fire a both a light and hot load over a Chrony. We then plug some critical data like the barrel length, case capacity, bullet, COL and we tweak the burn rate so that the calculated velocities meet the average of the the velocities obtained. From there you can load up your down the scale with that powder and be damn close.
After tweaking the burn rate I loaded my .375 for a node speed of 2 468fps and I Chrony'd the load at an average 2 473fps. Close enough for me.
What we then do is to "calibrate" a powder burn rate for a batch. We fire a both a light and hot load over a Chrony. We then plug some critical data like the barrel length, case capacity, bullet, COL and we tweak the burn rate so that the calculated velocities meet the average of the the velocities obtained. From there you can load up your down the scale with that powder and be damn close.
After tweaking the burn rate I loaded my .375 for a node speed of 2 468fps and I Chrony'd the load at an average 2 473fps. Close enough for me.
higgite
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Paint that thing blue and I know some guys that would by one.Design Integrated Technology, Inc (DIT) manufactures the Closed Bomb (Powder Bomb). It is used for determining the quickness and force of a test propellant sample.http://www.ditusa.com/closed_bomb.php
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