What Is The Story - New Hodgdon Burning Rate Chart

[fnbrowning]

After a pause in reloading for a many months, I reintroduced myself by reviewing data on loads for my favorite calibers. I came across the new Hodgdon Powder Burn Rate Chart and, WTF! the positions of some favorite powders have changed!

Looking at a Hodgdon Powder Burn Rate Chart <span style="text-decoration: underline">not more than 3 years old</span>, W-748 is listed faster than Varget. Varget and AA-2520 are neighbors, and are faster than Reloder 15.

Now, AA-2520 is listed <span style="font-style: italic">faster</span> than any of the powders I've mentioned! Reloder 15 is faster than W-748?? IMR 4320 is now between former neighbors Varget and W-748!

What has happened?? Is there been a change in the science of powder burning test methods, or have the majors mixed up new chemistries?

For instance, that 24-month old canister of W-748 in my workshop - - was it always faster than AA-2520 & Reloder 15, or was it always slower, being the previous burn rate data was <span style="font-style: italic">wrong</span>?

Or, or, is that 24-month old canister of W-748 now an obsolete chemistry that will cause myself (and all the data publishers like Sierra & Lyman) to have to retest all the shooting data because new batches of W-748 is a slower powder now???

 

[Top Cat]

Re: What Is The Story - New Hodgdon Burning Rate Chart

Call Hodgdon up and ask them their reasoning...they are helpful, friendly folks.

<span style="font-style: italic"><span style="font-weight: bold">If you have a safety problem or concern - DO NOT EMAIL - CALL US DIRECTLY 7:00am to 5:30pm Central Monday-Thursday : 913-362-9455.</span></span>

But generally speaking, burn rates are relative when powders are close in burning rate, as their relationship to other powders can change depending on what case they are fired in.

Whether a powder is assigned a higher or lower number on the chart doesn't mean that much in the real world. The burn rate chart is just there to give a very general idea, and the important info is contained in the actual load formulas as tested in the lab and published in the manuals.

TC

 

[Fuzzball]

Re: What Is The Story - New Hodgdon Burning Rate Chart

"What has happened?? Is there been a change in the science of powder burning test methods, or have the majors mixed up new chemistries? "

Nothing has happened. TC is right, burn rates aren't all that accurate and those that are close will change somewhat due to the cartridge/bullet combo.

All that matters is the loading data and it remains what it is too; books are general guides to be followed intelligently, not blindly.

 

[turbo54]

Re: What Is The Story - New Hodgdon Burning Rate Chart

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Fuzzball</div><div class="ubbcode-body">"What has happened?? Is there been a change in the science of powder burning test methods, or have the majors mixed up new chemistries? "

Nothing has happened. TC is right, burn rates aren't all that accurate and those that are close will change somewhat due to the cartridge/bullet combo.

All that matters is the loading data and it remains what it is too; books are general guides to be followed intelligently, not blindly.


</div></div>


Excellent post, fuzzball. Right on point.