Burn rate chart?????

[abunaitoo]

Almost every chart I find, there are not the same.
Some powders listings are way different.
What chart would be considered the most accurate????

[fredj338]

I've never seen way diff. At most, some powders will swap 1 or 2 places between diff charts. They vary per how the powders were tested. It isn't a big deal. You only use the burn rate chart to look for potential powders, not as a reloading guide. I would go with any BR chart from a powder manuf over one form a reloading site.

[sirgknight]

Like you, I have seen some burn rate charts all over the place. If you compare the charts from the powder companies, i.e. IMR, Accurate, Hodgdon, they are a mirror of each other. Their individual charts may list a powder that the others do not list, but the burn rate order remains consistant.

[Hardcast416taylor]

Like you, I have seen some burn rate charts all over the place. If you compare the charts from the powder companies, i.e. IMR, Accurate, Hodgdon, they are a mirror of each other. Their individual charts may list a powder that the others do not list, but the burn rate order remains consistant.

This is exactly the reason that I have more than 1 BR chart from different powder sources. Some show only their powders and few else, while others show about all the different named powders. I have and use powders from about all makers, so I like to see where they are in relation to other powders. About every 2 years or so I start gathering new and updated charts.Robert

[runfiverun]

it's because powder flip flops depending on how it's burned.
if it is tested in a 22 cal barrel versus a 30 cal barrel you will see a difference in powders that are quite similar in speed.

[BAGTIC]

In actual use powder burn rates can vary based on caliber, sectional density of projectile, charge density, pressure levels, ?. I believe published rates are probably based on performance in a closed 'bomb'. This would provide a relative comparison as all powders are being subject to the same test conditions. The problem is that those conditions are not necessarily analogous to a real world gun barrel.

[mdi]

Another thing about burn rate charts is they are not linear. Number 29 powder isn't necessarily the same amount slower than #28 as #32 is to #31. Yep, number 29 is faster than 30, but how much? The same "faster factor" as #22 is to #23?

Just having my first cup o' coffee so my definition is OK in my head, but maybe a little fuzzy in print...

[Chicken Thief]

As powders can wary +- several % from batch to batch then what is correct and whats is wrong?
And what when two powders is the same but has different names?
Like load tables it is but a guideline not concrete facts.

[felix]

Every lot of powder made will be different, and most especially when "improvements" have been made. The trend today is to go for cleaner burning and less ambient temperature sensitivity, sometimes for both at the same time! Smart labeling will indicate a completely different powder number for each lot when the lot has a "new" formulation. But then, the hobbyist will get thoroughly confused even more so than they are now. ... felix

[runfiverun]

felix just explained why I buy large amounts of the same powder at the same time. [32-48 pounds]
I then mix it all together.
and put it back into the containers.
once I have the load or loads I am gonna work with, I don't need to sweat changing it.
until I run out.
right now I have two separate density lots of 2400 which is a little frustrating.
but not an overly big deal as I already have the new lot of powder sorted out to replace the old one.
I just don't know what the next one will 'look' like.

[303Guy]

I used to record my loads with the lot numbers. Now I don't see the lot numbers on the cans. I have the idea that Hodgdon powders are more consistent from lot to lot due to blending at the factory. I get powders from the same factory under the factories name and it is not exactly the same as Hodgdon's due to absence of blending, I am given to believe. Load data is simply a quote from Hodgdon for most calibers but not for the 303 Brit!

What I would like to see are pressure traces for the powders I would like to use. Even better would be a pressure curve for each powder with incremental charge increases. I created such a graph by plotting powder charge and velocity for two powders. One powder had a steady curve while the other developed a rapid uphill climb toward the top. Not a powder to overload with! Some powders behave differently in different cartridges too. I assume that's why some powders are listed at max loads with lower pressure and velocity than others - those powders spike at higher loads. They would probably be more sensitive to seating depth. Anyway, It would be nice and useful but is not going to happen anytime soon.

[felix]

The VV powders are worth the extra cash when lot to lot consistency is REQUIRED for the very NARROW application on hand. There is less than 0.1 grain difference between the various lots I have obtained over the years for N110 and N105. I use these powders ONLY in my BR gun with the various boolits. Condom boolits do not need this level of consistency (in the powder). In fact, 4198 dropped from the hopper into the case has 0.4 grains total difference and does not show up on target at a hunnert using BR bullets. ... felix

[runfiverun]

little side note.
the best powder measure I have ever used for 4198 has been an old LEE.
4198 is the only powder it has ever dropped consistently.
it has been set on 24.5 grs for 20 something years now.

[catboat]

I like this burn rate chart:

http://www.lapua.com/upload/reloading/reloadingburningratechart2011.pdf

[felix]

That chart is too gross! Ball park only. ... felix

[catboat]

That chart is too gross! Ball park only. ... felix

I guess it means I like "gross."

The only issue I question with the Lapua chart is the position of H4198, seems to be placed "faster" than I thought. I don't use H4198, but just my take on it.

I like the chart's layout that gives lateral comparison of powders, along with the normal "fast to slow" lay out. If there is a better chart out there, which shows the "lateral" and "vertical" comparison, I'd love to see it.

[felix]

I would too! The chart would have at least 300 indexes, perhaps more, on the vertical scale. For example, each index slot would indicate the powder having a speed within a 1/300th of the slowest speed pertaining to present slowest cartridge powder made. ... felix

[rexherring]

Powder formulations have also changed over the years so old charts are sometimes off from newer ones. Use them as a ball park guesstimate but not a reloading guide. I like updated charts like the new Hodgdon chart.

[303Guy]

Some powders can swap positions on the burn rate chart depending on the powder, cartridge and load. Lil'Gun is one of them.

[jonp]

I thought the chart that is linked through the sight at the bottom of this page, castpics, to be pretty good. It even has a couple of the newest powders, 410 and 20/28, in it

[Shiloh]

They are close but different. Powders tested at the time. Lot #'s could change things slightly, hence the difference. They are charts only, NOT reloading guides.

Shiloh

[uscra112]

Nearest thing to an accurate "chart" for me has been the database in Quickload. I don't even look at paper charts anymore.