please explain why mixing powders is bad

The problem with mixing powders is we don't have the right test equipment available and using your own gun for this is suicide. That's the job of the powder manufacture and I assume they've already tested and developed the best combinations so why bother?
 
The short and sweat of it is: It is a recipe for disaster! You are playing the the goones of the Lion. It is impossible for the ordinary man to predict the outcome.

I had researched duplex loads long time ago as a result of un-burned flakes in my Marlin .357Mag's barrel. My conclusion was that it was not worth the risk of scrapping my gun and injuring myself.
 
Quit arguing/TRYING to reason with the TROLL, already. Anyone who persists in asking the same stupid-assed questions when credible and intelligent answers have been given by those who are [in the know], either cannot/will not ever understand, OR, is too damned STUPID to understand PURE LOGIC.

WILL
 
For an amateur home reloader, yep it can get dangerous because knowing the way powder A works and what powder B does when mixed is best done by those experts in powder technology. Powder A may produce XX pressure and powder B may produce XXX pressure but how do they react to each other?; cannot just average the pressures. Powder manufacturers do it all the time called blending, but they have the knowledge and equipment necessary to safely mix/blend powders and the experts to do so.
 
Come on ,guys!
Google Mr. Entropy and see what an off the wall freak this guy is! He's all over the place.Entropy is a calculated state of decline in a thermodynamic setting. (google it , as I'm no physicist) Don't feed him!!!
 
what causes secondary peak pressures?

Mysteries And Misconceptions Of The All-Important Primer. http://www.shootingtimes.com/ammo/ammunition_st_mamotaip_200909/ If the bullet moves to soon, it acts like a barrel obstruction, causing a 2nd pressure spike. The wrong components, when used with different reloading methods, can cause problems. Example >. http://thefiringline.com/forums/showthread.php?p=4928827#post4928827 But not resulting in a Kaboom. Like some of these >. http://www.photobucket.com/kabooom
 
Maybe a "real world" experiment could be to mix gas and diesel and put it into that auto you drive. After all they both burn just at different rates.
 
Mr Entropy's initial post, that was deleted, seemed so much off the wall and phony that I gave it the most facetious and far-side response that I could come up with at the moment (that by the way had nothing to do with convincing him not to mix powders). Then his current post seemed to be more forthright and perhaps more deserving of legit status. My thinking now is that he is anything but stupid about the subject and others, that he very well knows the fallacy of mixing powders and the potential results, and doesn't really care one way or the other about it (and probably doesnp't hardly care anything about reloading), and all he has been doing is just pushing our buttons to get our reactions rather than responses. He hasn't posted since #35 but if we keep feeding this thing with essentially the same replies it will never go away.
 
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mrentropy said:
Quote:

If you take two or more powders with different burn profiles, or even similar burn profiles, and mix them together there is no way of telling what would result in a safe load other than to experiment. Most people involved with handloading would consider such experimentation dangerous.
That makes sense.
Click to expand...

So why not use a really, really solid action & barrel, with a remote cable trigger, and put a piezo pressure sensor in the chamber (and maybe a few in the barrel too) with ns readout and a computerized data acquisition system, stand very far away, and get actual pressure readings?

Obviously that's a lot of work and $$$, but that would be the way to do it wouldn't it?
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The original post is a good question, in my opinion.

What you describe in the post I quoted is tantamount to building your own ballistics laboratory. Except for the "stand very far away" part. Most labs, you stand behind a blast barrier of some sort.

In the old days, mixing a fast powder with a slower powder was done occasionally. "Duplex Loads" I think they were called. Google the term. I don't know if they were mixed or carefully positioned (one next to the primer and the other packed further away and then everything packed tightly so no mixing would occur, for example). I never researched this very far.

Nowadays, the selection of powders (the occasional shortage notwithstanding) is pretty good and customizing/compounding one's own powder charges yields little advantage.

We seek to REDUCE all the risks and uncertainties we can. Most of us feel there are enough risks in our lives already.

Thanks for sparking a lively discussion. I understand (I think) that you are seeking to deepen your understanding of internal ballistics. I salute your quest.

Lost Sheep
 
I only know of one Cartridge that WAS originally loaded with three different powders . I well remember the coming out of the 454 it was original a three powder load . (but not mixed)




I knew a gun shop owner that would mix all the powder that came in on trade with reloading stuff . He had a big glass bottle and used it to load his Trap shells . He shot registered Trap for many years doing this and retired at the age of 70 .
 
The smokeless propellants we use are similar to the smokeless propellants used in rockets. Rockets operate at far lower pressures, though the load is huge because the pressure is in a big container. The propellant is almost always in the form or a thick cheesy solid substance. There are "layer" cake applications where one layer is a different burn rate, when that is burnt, the next layer might be faster, or slower, depending on the application.

Because our propellants are granular, you can't have the charge segregation you can have with rocket motors. Mixing different burn rate powders is too unpredictable. It might be possible to put a tube through the case centered around the primer. You could cast a solid propellant around that and have the primer ignite the top layer. Whatever gains there would be would be offset by the cost.
 
I think the bottom line is mixing powders is bad for the following reasons:

1) repeat-ability. Can you mix it exactly the same next time? And the batches of each powder add more complexity too it. The next batch of the same powder could require .4 grains to be the same as the last batch...so your doubling the variables of repeat ability...
2) Ease of use. Why mix when you can get sub MOA with 1 powder? Adding complexity without improved results.
3) Adding 30 grains of titegroup is not safe and that is 1 powder, etc. Just because you mix powders, doesn't mean its not safe by default. If you are doing 9 MM pistol, and your using 2 powders that say 5.0 grains is say 30,000 PSI, then obviously, mixing those 2 powders isn't compared with mixing titegroup and say...HS-6, which is a terrible idea.

no need to mix, #1 is all you need to not bother.
 
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