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Old August 19, 2013, 01:46 PM   #26
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I don't mix lots of the same labeled powder either....and while I know its probably just fine.../ I don't see a reason to do that either ( especially on loads for handguns where the min and max might be as little as 0.3 grain.... on loads for shotshells....where the min might be 15.7 grains and the max might be 19.8 would not be a problem mixing different lots, in my opinion.
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Old August 20, 2013, 07:22 PM   #27
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Several years ago, I loaded up some cartridges in which two powders were mixed by accident. I discovered the accident before I fired any of them, but since the two mixed powders were of similar burning rate and I had loaded an intermediate powder charge, I went ahead and fired some of them. They worked just fine. I put the remaining mixed loads aside and didn't use them. Years later, I happened to pull one of those bullets, and I saw that over time there had been some sort of reaction between the two powders, causing the powder to form large clumps. I am glad I did not try to fire any after they had been on the shelf for a long time.
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Old August 20, 2013, 09:10 PM   #28
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I have blended H414 and Win 760 before because I had about half a pound of each and I wanted to load it all for the same rifle and have it be consistent. But since 760 and H414 are the same powder it didn't bother me at all to blend them. If you are absolutely sure beyond the shadow of a doubt that two powders are the same, then I say blend away. Otherwise no.

buck460XVR explained it well.
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Old August 21, 2013, 05:04 PM   #29
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I have never mixed powder, but i did watch a video online with someone shooting black powder out of a glock with lead bullet. Odd stuff some people will do.
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Old August 21, 2013, 08:40 PM   #30
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Burn rates mean absolutely nothing when it comes to actually making the reloaded round

Mixing lots of the same powder is a perfect way to utilize the last remnants of that 8# jug with the new one you are about to open

Mixing different powders is for dolts with a death wish - don't do it
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Old August 21, 2013, 09:00 PM   #31
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I'll repost my text file of same powders. It's from MSDS sheets. Up until 2009 they seemed to have more detail than the current ones do, and that's where this comes from.

If you have tried two lots of the same type of powder separately and got the same velocity, then I can't see harm to blending, but then there's not purpose to blending, either. It is then just make work. If they are different, as other say, they could be blended to equalize the differences, but since you had to check them to learn they were different in the first place, why not just load them separately with corrected loads?

The reason to blend—to get just one large container of uniform powder—doesn't get you out of testing, as you have to check out the newly blended lot's performance anyway. The drawback was discovered by SteveNChunter, and that is that if one lot has reached the point, either due to age or to heat exposure, that its stabilizer is consumed and it is beginning to break down, you end up spoiling both lots put into the blend, where originally you would have just lost the one of them. Blending to lower variance is still a gamble. If one of the two is at about the nominal burn rate, while the other is at one extreme of the other, then you wind up with the combined lot pulled away from nominal. So, again, everything would have to be tested to find out what you've got in the new lot to make a decision.

Burn rate charts can appear all over the map. For example:
The problem with all of those charts, disagreements aside and in fact something in large part responsible for them is, you can't discern the size of the difference between two of them. Suppose three powders are almost the same, by your measuring method, then the next one on the list is a bigger step? How do you tell that on one of these charts? You don't. So, I really think the following types come a lot closer to being useful. You still don't know the size of the jumps, but at least they rank powders into groups that are close enough to one another to be pretty much be useful in the same applications.

They don't all agree 100%, either, but I still think they get a lot closer to being useful.
Powder Equivalents from 2009 MSDS sheets (some newer ones lack the  powder name information).
This is current as of (04AUG12) as far as I know.  I'll add data as I encounter it and change the information ast need be.  Note that bulk grade versions have wider burn rate specs and can vary significantly from the canister grades, which are controlled for burn rate by blending with held back fast or slow lots, as needed, to bring them in line.

     Canister      | Bulk Grade |       Canister         | Canister |      Canister        |
      Grade        |            |        Grade           |  Grade   |       Grade          |
                   | St. Marks  |                        |          |                      |
     Hodgdon       | Mil & OEM  |      Winchester        | Thales   |        IMR           |
                   |            |                        |          |                      |
HP-38--------------|-- OBP231 --|- 231 ------------------|----------|----------------------|-
                   |   OBP124   |  AALite (WFL)          |          |                      |
Titewad            |   OBP132   |                        |          |                      |
Tightgroup --------|-- OBP242 --|------------------------|----------|----------------------|-
                   |   OBP465   |  Super-Handicap (WSH)  |          |                      |
Longshot           |   OBP473   |                        |          |                      |
Lil' Gun ----------|-- OBP516 --|------------------------|----------|----------------------|-
Hybrid 100V        |   SHP771   |                        |          |                      |
                   |   SMP224   |  AutoComp              |          |                      |
-------------------|--- WAA90 --|- WST ------------------|----------|----------------------|-
H110               |    WC296   |  296                   |          |                      |
HS-6               |    WC540   |  540                   |          |                      |
-------------------|--- WC748 --|- 748 ------------------|----------|----------------------|-
H414               |    WC760   |  760                   |          |                      |
H335               |    WC844   |                        |          |                      |
BL-C(2)------------|--- WC846 --|------------------------|----------|----------------------|-
H380               |    WC852   |                        |          |                      |
US869              |    WC869   |                        |          |                      |
-------------------|-- WMR780 --|- Supreme 780 ----------|----------|----------------------|-
                   |   WXC170   |  WSF                   |          |                      |
Clays              |            |                        |  AS30N   |                      |
International Clays|------------|------------------------|- AS50N --|----------------------|-
Universal Clays    |            |                        |  AP70N   |                      |
H4227              |            |                        |  AR2205  |IMR 4227 second source|
H4198 -------------|------------|------------------------|- AR2207 -|----------------------|-
Benchmark          |            |                        |   BM2    |                      |
H322               |            |                        |  AR2219  |                      |
-------------------|------------|------------------------|- AR2210 -|- IMR 8208 XBR -------|-
H4895              |            |                        |  AR2206H |                      |
Varget             |            |                        |  AR2208  |                      |
H4350 -------------|------------|------------------------|- AR2209 -|----------------------|-
H4831              |            |                        |  AR2213  |                      |
H4831SC            |            |                        | AR2213SC |                      |
H1000 -------------|------------|------------------------|- AR2217 -|----------------------|-
Retumbo            |            |                        |  AR2225  |                      |
H50BMG             |            |                        |  AR2218  |                      |
-------------------|------------|------------------------|- AR2215 -|IMR 4198 second source|
                   |            |                        |  AS25BP  |IMR Trail Boss        |
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Old August 21, 2013, 09:16 PM   #32
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Another problem with judging powders purely on burn rate is the fact that some powders have more potential energy than others. Two powders with near identical burn rates can yield notably different pressures.
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Old August 22, 2013, 03:29 AM   #33
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I'm not about to claim to know as much about mixing and reloading as any of you folks, I think I will stick to the advice I read in my Lymans manual. "If you are thinking of mixing powders or you believe the powder manufacturer for safety reasons are shortening the load data and you want to over load. Then it is time to find a different hobby! D.
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Old August 22, 2013, 07:42 AM   #34
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Yes! And not only that, but different types can have substantially different burning characteristics, with very different pressure curve shapes due to differences in how progressivity is managed, so the value of the peak pressure cannot be determined even by having both burn rate and energy content. QuickLOAD has 7 different characteristics for each powder, and changing any of them will change the peak pressure prediction. There is a rough relationship between burn rate and charge weight, but the correlation is not tight enough to let you determine a safe charge weight from it. The burn rate can suggest a powder may be appropriate for an application, but not exactly how much you will need to use in that application.
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