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Posted: 9/10/2008 4:43:38 AM EDT
| Although I know it's forbidden to mix powders, in the throws of a senior moment I inadvertently dumped ~500 grains of AA 2230 powder into a full 1# container of IMR 3031. So, now I have a full 7000 grains of IMR 3031 contaminated with 500 grains of AA 2230. In spite of the manufacturing differences (one is ball powder, and the other is stick) they usually have very similar charge weights for a given bullet weight and velocity. So, with a ratio of 14:1 IMR 3031 to AA 2230 do you think it's safe to use this powder for .223 Rem and 30-30 Win reloads. I typically charge to at least 1 grain under max loads listed in the Speer and Hornady manuals. |
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The densities are very different. You can get a significant amount of AA2230 into the spaces between grains of 3031. Consider this your latest tuition payment in the college of life. ETA, You might be able to take advantage of the difference in grain sizes and sift the AA2230 out of the much larger grained 3031. I wouldn't do it. I'd take my lumps and dispose of the contaminated powder, but there's an option. |
Midlength.| Interesting Problem. On the powder burn rate chart these powders a only 4 apart. So the burn rate being nearly the same it may make a good fire forming concoction. Personally I would can it. If I spend my time to load a round I like it to be as good as possible. |
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Your looking at less than $30 to learn to 1. read your notes before dumping powder back in a container 2. put only one container on your bench at a time 3. fertalize your yard / start a quick brush fire. a pound of powder really isn't that big of a cost compared to the damage mixing can cost. ETA: Did you really expect any other answer? |
A burn rate chart shows a ranking by speed, but not a quantitative difference, and they might not always stack the same way depending on the details. "Four apart" is pretty vague and I would use extreme caution before making a substitution based on this information alone. |
| I got pretty much what I expected from the forum; although I did expect at least a couple of responses that would advance a receipe or two. I will dump the powder, but I am curious about why powders with very similar burn rates, and almost identical charge weights for a given bullet / velocity combination cannot be mixed. If we defied the law of averages and the powder dispenser threw 25 grains of IMR 3031 we would be GTG; if the dispenser threw 25 grains of AA 2230 we would likewise be good to go. Why then if the dispenser threw 12 grains of one and 13 grains of the other it would be considered unsafe even though the charge would be 25 grains of similar powder. Again, this question is asked out of curiousity---I will take your unanimous advise and create some original fireworks. And, thanks for your time and consideration in an effort to keep this old guy in one piece. |
AA2230 is denser than IMR 3031. The cavity in the powder measure that would dispense 25 grains of 3031 would be considerably larger than the cavity that would dispense 25 grains of 2230. Additionally, the 2230 grains will fill the spaces between the 3031 grains like sand would fill the spaces between marbles in a glass. You cannot ensure a perfect distribution of 2230 grains within the 3031 grains. You also don't know how the exact pressure curve of the one powder would affect the pressure curve of the other. |
I was going to say the same thing but he said weight, not volume. |
He said "If the dispenser threw" which implied to me that he was using a volume measure and, as is pretty common, referring to the output of same incorrectly as weight. If the charges were trickled to exact weight, there would still be the inconsistent mix of type and the unpredictability of the mixing of pressure curves. |
| It's the weight vs. volume debate that peaks my curiousity. The powder is dispensed by volume once we calibrate the volume to a given weight. So, in the final analysis what we end up loading is xx grains of powder even though it was dispensed by volume-density notwithstanding. Once again, please do not misinterpret my questions / responses; I'm just trying to understand the safety issues behind the 'do not mix' cautions and warnings. Now if the principal issue is the chemical differences between the powders, and one powder might act as a catalyst for the other, then I would better understand. In cases like that there would be completely new temperature and pressure curves not defined by either powder alone. Or, maybe I don't fully understand the dispensing steps in the charging process; I always thought you threw a certain volume of powder, weighed it, adjusted the dispenser, threw a volume, weighed it.....until you got to the exact volume that was equal to the weight in grains you wanted for the bullet-powder-velocity combination you were looking for. If this is wrong that may be my problem in grasping the finer points of the discussion. And, again thanks to you all of you who have chosen to voice your position in response to my questions. |
What you are missing is that you cannot ensure a consistent mixture of dense grains and less dense grains. Since you cannot control how much of each powder is in any particular throw, you cannot accurately predict weight based on volume. Even if you could somehow control the mixture and ensure that consistency, you cannot predict how the mixture of the 2 powders will affect the pressure curve. That each powder used alone has a similar charge weight indicates that each will reach a similar maximum pressure. But where in the curve does each powder reach maximum pressure? Could one powder reaching peak pressure earlier, cause the other to accelerate its burn rate? If it does, what will the new maximum pressure be? There just isn't any way for a hobbyist to know... |
Looks like a $20 fireball in the backyard.........
the speed a powder burns depends on its pressure. (light off 25 grains in open air and look how long it takes to burn) if powder "A" creates a sharp pressure rise initially, but burn speed tapers as pressure rises while powder "B" creates a slower pressure rise initially, but speeds up as pressure rises. when mixed, powder A peaks the pressure quickly causing powder B to burn faster you get a total pressure that is higher than the two powders individually. Its these two pressure profiles and how they will interact that is unknown. combine that with a huge number of variations in mixtures. the safest thing to do is dump the powder. |
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"the principal issue is the chemical differences between the powders, and one powder might act as a catalyst for the other" I Think you have grasp the problem. Some Benchrest guys or shooters will mix powders for a specific reason. This is not done haphazardly. If you have the means to measure flash rate and happen to have a homemade manometer to capture the pressure rise it is possible to accomplish. Some of these shooters also have scared up faces, just saying. I think you should dump it before you forget which bottle of powder was mixed. This is also something to think about when you see cans of un-sealed powder at pawn shops, gun stores or estate auctions. You really dont know where its been or how treated. |
I had a brain fart in which I dumped some AA#5 into a canister of AA#7. It was painful but I just accepted the fact that it was now waste material. On the plus side, it made a wonderful burn.  It's one of those things that if you weighed EACH charge, you MIGHT be ok. But sadly no one, literally NO ONE except a propellent engineer/scientist can actually give you a safe answer that doesn't begin with 'all you should do is' and ends with 'dispose of it safely' .....sorry |
| The variety of responses has indeed given me a much better understanding of the 'cautions and warnings' related to mixing unlike powders. hsvhobbit stated "you MIGHT be OK if you weighed EACH charge"; that is pretty much where I was originally headed in an effort to off-set the effects of density differences between the two powders. But, now that I have been taken to school on the unknown effects of the chemical differences (which I didn't originally consider) I have taken your collective advise and dumped the powder in my yard. At first I gave consideration to a special fireworks display, but that would take time to plan, and the longer I stared at that 1# container of powder the more tempting it would be to experiment. So, it's gone and thank you all for a enlightening discussion of safety, chemistry, physics and common sense. |
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