Lee 2ndEd, Hodgdon, Ramshot -- Bad Powder Burn Rate Charts?

[Dannix]

N133 is listed as faster than IMR3031 [Edit:Same on ramshot's burn rate chart too!]
http://www.ramshot.com/powders/burnrate.php
Vihta Vuori N133
Hodgdon H4198
IMR 4198
Accurate XMR 2015
Alliant RL7
IMR 3031

But, Hodgdon lists N133 as slower than 3031.
http://www.hodgdon.com/burn-rate.html
IMR, Co IMR 3031
VihtaVuori N133



Varget is listed as faster than H4895 in Lee 2ndEd:
H-Varget
748
BL-C(2)
2460
H335
H4895

But ramshot lists Varget as slower.
http://www.ramshot.com/powders/burnrate.php :
99. Hodgdon H4895
100. Accurate XMR 2495
101. Alliant RL12
102. IMR 4895
103. Scot Brig 4065
104. Vihta Vuori N135
105. Hodgdon Varget


So what's up? :?:

[side rant]
These kinds of discrepancies from trusted sources mildly freak me out. I'm starting to get frustrated with manual data too. I'd like details I'm not getting, but I suppose if reloading manufactures gave such detail they could work themselves out of a job? I'd like not only what test components are being used (my Lyman gives it, Lee doesn't), but associated empirical data, like case capacity for the given case with given bullet the the given OAL, variations in the case capacities of the particular test case choice for a give calibre. I'd like precise, detailed numbers on powder burn rates, consistency over the years the reloading manual developers have tested them, trends as the powder is used in different case capacities, fps trends as different weight bullets are used at a constant case capacity and at a constant OAL.

I guess when it comes down to it, I don't want "cookbook" info like a freshman chemistry student. I want nitty gritty details that I can make my own extrapolations with. :-?

[felix]

Consistency of verification methods do not exist between the listers. What would be a definite improvement would be a demarcation line between "application" groups of powders. For example, in the 308W using a 170 nominal grainer boolit my lot of 3031 is 7 grains slower than my lot of 4198 at a guestimated 30K cup each, both IMR bought in the 90's at the same time from the same distributor. A listing demarcation line should be drawn between these two powers. Your last listing shown would be shown as a single group with a line above and below the group. These powders can exchange places at will depending upon application and no individual should appear in a proceeding or following group. Experience is the ONLY way to determine what individual powder APPEARS correctly when assigned to a group. ... felix

Also, single base powders are being modified especially by Hodgdon for intentional formulation changes. This really presents a problem like what is shown in your IMR, Co IMR 3031;VihtaVuori N133 group. If the powders were before changes, the order would be reversed. ... felix

[watkibe]

Powder manufacturers tell you that the burning rate data is only accurate on their testing equipment, and that other sources of data may vary.
Pressure measurement has become a pretty exact scince compared to the old lead or copper crusher units, but not all pressure measuring set-ups are exactly the same. Therefore, there will be differences in results from different sources.
Besides which, these same manufacturers will tell you that the burning rate is a relative measurement, provided soley for information's sake, so that you can look for published data for other powders that are close on the burning chart to the one you are using. I don't recall anybody recommending extrapolation of any type, and in fact I think some of them say that burning rate charts should definitely never be used to decide on charge weights.

[Bloodman14]

watkibe, +1! Never use burn rate charts to extrapolate data, not even from the same manufacturer. H335 has almost the same burn rate as H4895, but 2 grains difference for the same pressure in a 308 Win. using a 180 gr. jacketed bullet (Hodgdon's Annual manual).

[WILCO]

I use the load data as published for a specific application and I don't get upset questioning it.
Life's too short.

[Jim]

If it's of any use, HERE (http://www.reloadbench.com/burn.html) is the biggest powder burn speed chart I've found so far. Nothing says this one is any better than the next. It just has lots of data.

[Rocky Raab]

What's more, there is NO standard unit of measurement for burn rate. If there were, burn rate charts might be of some use, but since there is no such agreed-to unit, lists are almost meaningless. Besides, all those "one through..." charts pretty much useless anyway because even if two powders are absolutely identical, they have to list one before the other.

Finally, burn rates change in actual use, depending on the exact primer/cartridge/bullet/gun being used.

[1Shirt]

All of the burn rate charts published by all of the mfgs of reloading equipment/powder/blts, etc are guides for reference only. This is but one more reason to have a number of different manuals for reference. Like Reagan said "Trust but Varify!".
1Shirt!:coffeecom

[spqrzilla]

The best bet is to not use the burn rate chart for anything. I never do. It is meaningless.

[Lee]

Extrapolation bad.
Interpolation good!
:wink:

[KYCaster]

Good advice from everybody so far. I agree that burn rate charts can't be used to develop load, but the chart that Jim posted is often the first place I look when I get a powder I'm not familiar with.

For example, I once won two lbs. of Scot Solo 1000 at a pistol match.(No I didn't take first place, it was a random drawing. :-P ) I didn't have a clue what it is good for, so the first place I looked was a burn rate chart. I found it's one of the fastest powders listed so I looked for published loads in 38 Spl. Beats thumbing through a loading manual looking for a cartridge that uses it.

That's pretty much the only use I've found for burn rate charts.

BTW...AFAIK Lee doesn't do any load development. Any loads they publish are copied from some other source. I'll use the Lee manual to find another source for a load, that's about it.

Good luck
Jerry

[MakeMineA10mm]

Consistency of verification methods do not exist between the listers. What would be a definite improvement would be a demarcation line between "application" groups of powders. For example, in the 308W using a 170 nominal grainer boolit my lot of 3031 is 7 grains slower than my lot of 4198 at a guestimated 30K cup each, both IMR bought in the 90's at the same time from the same distributor. A listing demarcation line should be drawn between these two powers. Your last listing shown would be shown as a single group with a line above and below the group. These powders can exchange places at will depending upon application and no individual should appear in a proceeding or following group. Experience is the ONLY way to determine what individual powder APPEARS correctly when assigned to a group. ... felix

Also, single base powders are being modified especially by Hodgdon for intentional formulation changes. This really presents a problem like what is shown in your IMR, Co IMR 3031;VihtaVuori N133 group. If the powders were before changes, the order would be reversed. ... felix

Study this, learn this, believe in this. This is the best way to think about powders on a burn rate chart. I have a burn rate chart I made up with over 220 powders on it, and this is what I did. I think Lapua or Norma put out a chart like this too, and I really like it. I grouped them by general speed. Within the groups, the relative positions mean nothing. In-between the groups, general conclusions about what powders are always slower or faster can be made. Within the groups, other factors can differentiate powders from each other, such as single-base/double-base, extruded/ball/flake, and other things, such as whether it's temperature insensitive, position insensitive, clean-burning, etc.

[Jim]

I would NEVER trust a burn speed chart as gospel. As has been mentioned, I use it as a rough guide to where a particular powder is in reference to both ends of the spectrum.
Recently, Jerry Bartlett at G I Brass listed some stuff that SUPPOSED to burn like Herco. Not ever having used Herco, I went to the chart to give me an idea of where it is.
As with ALL powders that I'm not familiar with, I start low with fillers and work up slow.

[Dannix]

I wasn't referring to using burn rates for extrapolating, but the data I wished they were publishing that they weren't, like case capacity of the chosen components et al that was listed in the "side rant" above.

That clarified, I've found Accurate does have a nicer burn rate where where powders are listed in a format more helpful that just one to umpteen, but one where rough equals are communicated.
http://www.accuratepowder.com/products/burn-rates/

The differing testing methods implemented resulting in the different burn rate chart rankings -- Any information to be had that goes into the different testing methods used by different powder manufacturers, and which techniques may more closely correspond to actual loading for different calibres?

Thanks for all the input.

[Rocky Raab]

Powders aren't usually tested in cartridges to determine a burn rate. They are tested in closed containers (called "bombs" not surprisingly!) and don't involve other components that would mask or confuse the results. That's one major reason why burn rate charts are less than useful: the results have nothing to do with cartridges or guns.

[MakeMineA10mm]

Dannix,
That's very much like the one from Lapua, and is the way all burn rate charts should be made, IMO. It gives a much clearer idea that some powders are so close they interchange positions.

I made mine slightly different so that all the other characteristics of the powder could be listed, such as it's shape, other qualities, and if it has another name by another manufacturer (like all the ADI powders that Hodgdon is marketing in the US).

Glad to see Accurate has put out that chart. That's very good!

[Rocky Raab]

That Accurate chart is good but still has some very debatable listings. W231 is placed on the same "speed" line as Bullseye and Clays, yet HP-38 is six lines lower/slower. However, W231 is NOT as fast as Bullseye, and is in fact the same powder as HP-38.

I've seen several charts like that one, and I use one on my website that I changed and added to. The only drawback to it is that the lines are not uniform "speed rates" apart. That's because there is no unit of measurement for burn rate - something we genuinely need but which the various companies can't or won't agree to. As is, we can generally see that a given powder is faster than one on a line below it - but not by how much. That "how much" is what is still missing.

[MakeMineA10mm]

Yes, I agree. The second point you make is why I always liked Alliant's "Relative Quickness" number.

[Dannix]

Powders aren't usually tested in cartridges to determine a burn rate. They are tested in closed containers (called "bombs" not surprisingly!) and don't involve other components that would mask or confuse the results. That's one major reason why burn rate charts are less than useful: the results have nothing to do with cartridges or guns.
That I get and don't mind too much, except the by-how-much issue Rocky Raab posted above. I'm not really knocking the powder manufacturers, though it would be nice if they would at least standardize on a testing methodology.

I wish those publishing Reloading Manuals got way more geeky, more quantitative in the reloading data they provide though. This is where I would like to see "real life" testing data. Maybe I'll fill this need someday(Is there a market, or am I the only one interested, a market of one? I don't know). I'm just trying to keep my head above water for now though.


burn rate charts ... I made mine slightly different...
Link?


That Accurate chart is good but still has some very debatable listings. W231 is placed on the same "speed" line as Bullseye and Clays, yet HP-38 is six lines lower/slower. However, W231 is NOT as fast as Bullseye, and is in fact the same powder as HP-38.
Yeah, it makes you wonder. I really wish they would at least date stamp the data. 20-year old data or data gained from different testing processes is worth something, sure, but I definitely want to know about it. My rant in part is the lack of transparency.


I use one on my website that I changed and added to.... That "how much" is what is still missing.
Link (http://www.reloadingroom.com/index_files/Burn%20Rates.htm), for those also interested. Regarding the second comment, that's what qualitative data gives you. It would be nice if they published their quantitative data.

[Rocky Raab]

Agreed back at ya. Alliant's number is very close to what the industry ought to adopt - if they could only agree on a single unchanging powder as THE reference. A few hundred pounds of a reference powder would last for centuries as the benchmark for the rating system, and every powder could be tested and assigned a speed number.

That wouldn't account for the burn rate changes that cartridge shape, bullet and gun dimensions and atmospherics can induce, but it would still be a huge improvement over what we struggle with now.