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, ***! the positions of some favorite powders have changed!

Looking at a Hodgdon Powder Burn Rate Chart not more than 3 years old, W-748 is listed faster than Varget. Varget and AA-2520 are neighbors, and are faster than Reloder 15.

Now, AA-2520 is listed faster 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 wrong

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

 

[BBDartCA]

sloppy paperwork maybe?

http://www.hodgdon.com/burn-rate.html

 

[fnbrowning]

sloppy paperwork maybe?

http://www.hodgdon.com/burn-rate.html

Well, those 'old' values were well established, and widely referenced. For instance I have a Western Powders, and another chart that collaborate the 'old' values.
As to the 'new' chart, (your link) I can't imagine what caused the changes, but sloppy paperwork is not something I'd accuse Hodgdon of. . .

 

[kingmt]

if 3different powders all have the same burn rate 1 of them must be listed first. Then there iis the fact that 2 explosions won't creat exactly the same pressure. Also different lots will be somewhat different.

I wouldn't drive myself crazy trying to figure it out. It is just another tool pick your favorit & use it. I like a stright claw Estwing to fram with but someone else will tell you why a curved claw Stanly is better.

 

[7.62 Nato]

Has the loading data changed also, or just the chart?

 

[Walkalong]

Just the chart, and some of the pistol powders make more sense where they are now..

 

[USSR]

Looking at a Hodgdon Powder Burn Rate Chart not more than 3 years old, W-748 is listed faster than Varget. Varget and AA-2520 are neighbors, and are faster than Reloder 15.

Now, AA-2520 is listed faster 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!

Don't sweat it. These charts are not written in stone, and the charts put out by different companies don't agree with each other. Just take them for the degree to which some powders are similar and perhaps useful for a particular cartridge/load.

Don

 

[rcmodel]

I was gonna say.

I have burn rate charts going all the way back to 1962 from several different sources.

And none of them agree 100% exactly on everything!

All they are good for to me is sorting out obscure powders I never heard of to determine if they were pistol or rifle powder.

The problem with trying to use them for anything else is, the actual burn rate is cartridge specific to a great extent. Compare one powders data to other powders in 22-250 and a 45-70 for instance.

They both can probably both use it, but they don't align with the stars any better then they align with the pressure & velocity achievable with another powder that is "supposed" to be one or two clicks faster or slower on a burn rate chart.

rc

 

[Kernel]

IMO Accurate Powder's burn rate chart is one of the better online carts. They keep it up-to-date, too. The "2-D" format is more useful (instead of simply listing powders lineally - 1 thru 100, or whatever). A 2-D chart can show powders with similar burn rates at the same level, and it has a variable range between powders - allowing for a sense of scale.

http://www.accuratepowder.com/wp-content/uploads/2010/12/burn_rates.pdf

 

[mgmorden]

Odd. That Alliant chart shows Red Dot and Promo being slower than Bullseye. I guess since its their powders they know best, but I always though those two were faster than BE.