Why do companies publish powder burn rate charts

If as every chart says don't use chart as guide to create loads only used published data, Eg http://www.accuratepowder.com/wp-content/uploads/2010/12/burn_rates.pdf, and virtually all threads/guides say only use published data, why do the companies publish the charts?

Perhaps for identifying substitute powders. If someone typically used W296 for their loads, but in a powder shortage could not get W296, they could perhaps use a powder burn rate chart to look for other powders with a similar burn rate. They certainly could not use the replacement as a direct substitute, certainly not without conducting research, but it could point them towards replacement powders to investigate.

They're covering their asses in case you blow your hand off.

Because if you know you want a slower powder, or a faster one, it gives you an idea of which powder to try.

Then you use published load data for that powder. Makes sense to me!

So you can make a determination of selecting a similar powder like 4064 4895 h4895 instead of using the wrong powder like Retumbo in your m95 3006 spanish mauser at the same charge weight.

Snav said:

If as every chart says don't use chart as guide to create loads only used published data, Eg http://www.accuratepowder.com/wp-content/uploads/2010/12/burn_rates.pdf, and virtually all threads/guides say only use published data, why do the companies publish the charts?

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That sir is a darned good question.

My opinion, while perhaps good for making certain broad comparisons and generalizations, burn charts don't really have a whole lot of practical nuts and bolts utility. And you certainly don't want to assume that you can casually use the same load specs for two different powders that are listed as being "close" on the burn chart.

You're interested in alternatives because you need better accuracy? More velocity? Better case capacity utilization? Can't find your favorite powder?

Better IMO with any of these possibilities and more to bypass the burn chart, and look for powder options in your industry published load data. It is here where you know that load testing has taken place. "Close" with no data doesn't really help you.

During the most recent powder crisis in 2013-14, when finding powder was difficult, and finding the same powder twice in a row oftentimes damned near next to impossible, it was common practice for many to research and carry a list of applicable powders for the cartridges they load. I know I did it. Such a research exercise, for those who hadn't had reason to research before, would also yield valuable information in terms of powders that tend to be more "universal" in nature, across multiple cartridges that may be applicable to a particular reloader. Say you load .223/556 and .308 as an example.....any powder that might work well for both that I could snag if I should see it? That sort of thing. But even here, I'd suggest that your really worthwhile information is to be found in cartridge specific industry published load data, rather than burn charts.

Uncle Duke said:

That sir is a darned good question.

My opinion, while perhaps good for making certain broad comparisons and generalizations, burn charts don't really have a whole lot of practical nuts and bolts utility. And you certainly don't want to assume that you can casually use the same load specs for two different powders that are listed as being "close" on the burn chart.

You're interested in alternatives because you need better accuracy? More velocity? Better case capacity utilization? Can't find your favorite powder?

Better IMO with any of these possibilities and more to bypass the burn chart, and look for powder options in your industry published load data. It is here where you know that load testing has taken place. "Close" with no data doesn't really help you.

During the most recent powder crisis in 2013-14, when finding powder was difficult, and finding the same powder twice in a row oftentimes damned near next to impossible, it was common practice for many to research and carry a list of applicable powders for the cartridges they load. I know I did it. Such a research exercise, for those who hadn't had reason to research before, would also yield valuable information in terms of powders that tend to be more "universal" in nature, across multiple cartridges that may be applicable to a particular reloader. Say you load .223/556 and .308 as an example.....any powder that might work well for both that I could snag if I should see it? That sort of thing. But even here, I'd suggest that your really worthwhile information is to be found in cartridge specific industry published load data, rather than burn charts.

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Good points. A question for you, if you know.

I’ve had the most success in developing loads, particularly softer shooting loads, by looking at pressure specifications and muzzle velocity for different powders. I haven’t looked, but I’m wondering if there’s a correlation between these numbers and powder burn rates. What are your thoughts?

I know there are so many different factors to consider, not just a single one. Degree of crimp, seating depth, How close to the lands the projectile is, these are all factors that can change pressure quite a bit even when powder and projectile are exactly the same. Kind of thinking about it as I’m writing, but would be interested to hear your input.

50 years ago, burn charts meant something as there far fewer powders. The spread between the powder speed was much larger due to fewer types of powders. Today, I don't think they are worth much as there is much more information available for making powder decisions. When I was a kid, I think the powder burn list was probably about 30 powders if that.

Burn rate charts point you to load data. If you have been using one powder and getting good results then the burn rate chart will point out powders with similar burn rates from other manufacturers. Also if you see a recipe that uses a powder you are not familiar with you can check the burn rate chart for an indication of how close it may be to what you are currently using. Just one more bit of data to use.

MG in MD said:

Good points. A question for you, if you know.

I’ve had the most success in developing loads, particularly softer shooting loads, by looking at pressure specifications and muzzle velocity for different powders. I haven’t looked, but I’m wondering if there’s a correlation between these numbers and powder burn rates. What are your thoughts?

I know there are so many different factors to consider, not just a single one. Degree of crimp, seating depth, How close to the lands the projectile is, these are all factors that can change pressure quite a bit even when powder and projectile are exactly the same. Kind of thinking about it as I’m writing, but would be interested to hear your input.

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Hmmm......

MG, I'm not sure what you're looking at (or perhaps looking for exactly) when you are assessing the data you see, especially since you mention data that might produce more desirable softer loads. Thinking you're seeing 2 numbers where available, as some manuals show pressure in addition to velocity.....where others don't. Lee manual comes to mind. Just not sure what you see those numbers telling you, in terms of being favorable vs. unfavorable for softer loads.

I would think that there's indeed a measurable ranking relationship between listed powder chart burn rate, and when peak pressure (in addition to how much pressure) is actually achieved. Not a clue have I though, in terms of how one could measure either pressure or peak pressure, outside of a ballistics lab. And where similarly "charted" burn rate powders aren't listed? Well, maybe that particular powder wasn't tested. Or MAYBE the relationship between the velocity and pressure and/or peak pressure figures wasn't, for whatever reason, what the guys with the degrees actually wanted to see. Just a thought as to one of many reasons why I want the labs.....and not me..... to test the unknowns and do the really heavy experimentation.

Take a look at the chart in the article below. It cites another element besides pressure and velocity.......a timeline of what....as well as when.....peak pressure is achieved with a particular example cartridge. It may surprise many to see that where pressure is highest, velocity is comparatively minimal to what will ultimately be achieved. While I don't know for certain, I would certainly think that these sorts of measurements would apply to comparisons that are part and parcel of ultimate rankings, regarding what falls where on powder burn rate charts.

https://gundigest.com/gear-ammo/reloading/bullet-ballistics

John from MD said:

50 years ago, burn charts meant something as there far fewer powders. The spread between the powder speed was much larger due to fewer types of powders. Today, I don't think they are worth much as there is much more information available for making powder decisions. When I was a kid, I think the powder burn list was probably about 30 powders if that.

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That's a great point John, and of course there's more and more powders being introduced every day.

2016 saw IMR come out with Red, Green, Blue, Unequal and Target.

Think of Alliant's offerings, and it's not hard to figure out what much more familiar Alliant powders are being targeted by their competitor. Similarly, where these new offerings would likely fall on the burn chart.

Actually it is the opposite, with today's plethora of powder product lines.

Back in the day when mainly IMR and Hogdon ( which half the time had identical powder numbers ) it was easier to know what was what . Today I wouldn't know rough equivalents between Vita Vhori and Western Powder Co without a chart.

Meant in terms of but another example of redundancy.

What do we have today, 150-200 powders?

Burning rates of powders behave differently due to lot- lot inconsistencies and can have a cumulative effect when ignited in cartridges of nearly the same volume. Its the little plug on the end that determines that.
The release of energy by burning is called deflagration, The rate of energy released is the burning rate. Burning rate scales are not absolute, they are approximate. What determines energy is how the cartridge is loaded even down to how the mechanics of the arm they are fired in specs out to. Thats why a particular charge or type of powder behaves when lit and why a light charge in a magnum rifle can be just as dangerous as an overload. Less powder is able deflagrate and allow a higher energy release at a faster rate
Published loads have been identified as performing to a standard determined by testing. Start low and work up. What works in your rifle may exhibit signs of pressure at several grains less in my rifle.
Its also the same reason that nearly alike powders may not achieve the same velocity as factory produced loads and pressure signs can be experienced way early when trying to duplicate ballistics. Canister vs, bulk powder.
One little cartridge you can hear the powder rattle, and bulk factory loaded ammo no shakey.
Next thing you know you have to beat the bolt open with a mallet because there was plenty of more room of brand A powder to fill the case up to get that extra 100fps.

The cartridge I was investigating 18mo ago is The 25-45SRC and before much info was available Sierra suggested that using 6mm-223 data would be a place to start.

Sharps came out with data and among other things it not only stated that Ramshot X-terminator came closest to their factory loads but that AA2230 and X-Terminator were the same powder. A quick glance at the western loading guide, at least in the 223-5.56 pages, confirms this as both powders are listed with the same data.

I found online that many powders are rebranded and several are identical. I can't find the list again that showed which were identical but found this info on the ADI webpage.

IS HODGDON PROPELLANT THE SAME AS ADI PROPELLANT?
ADI export a range of propellant to the US market where they are rebranded by Hodgdon Powder Company. We share reloading data and technical information with Hodgdon, which helps keep our products at the cutting edge of performance and quality, also the sizeable volumes of Aussie-made powder we export to the US help keep local manufacture economically viable.

ADI / Hodgdon Propellants Equivalents

ADI Powder Hodgdon / IMR naming
Trail Boss Trail Boss
AR2207 H4198
AR2219 H322
BM2 Benchmark
Bench Mark 8208 8208 XBR
AR2206H H4895
AR2208 Varget
AR2209 H4350
AR2213H / AR2213SC H4831 / H4831SC
AR2217 H1000
AR2225 Retumbo
AR2218 H50BMG