Powder cross contamination

barnfrog said:

Every time I finish loading a batch of ammunition with a powder measure or trickler, I'm always careful to get every last particle of powder out of the device so that I'm not inadvertently mixing powders the next time I use that piece of equipment. And every time I'm doing that, I always wonder how much powder mixed with another powder would produce noticeable changes in performance. If three granules of AA#9 got mixed into a 5.0-grain charge of Unique, would I be able to tell when I fired that round? I'm guessing not, but what about a tenth of a grain, which would be about 2% of the charge? At what point does mixing powders, intentional or not, become dangerous?

I'm not going to change my practice of removing every last bit of powder when I'm done with a piece of equipment, because I don't want to learn the answer to my question by mistake. I'm just curious. I suspect the answer varies based on which powders are involved.

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I'm like you.

Think about it...

After I use my drop, I empty it out. I even spin it off the press, turn it over, and knock on it to get everything out. But... so what if I didn't?

When I go to use my drop again... with a different powder... what do I do? I fill the hopper back up, set the measure near where I think it needs to be, and drop about 10 drops to get the powder to settle. Whatever powder might have been left in the drop just passed through. I uncork the top and pour that back in... so it is now so diluted as to make zero difference anywhere in the loading cycle. I make a few more drops, fine-tuning the weights with the beam scale, and then, finally, I'm off to the races.

As far as my trickler... same same... I dump it out, and then knock it out. Even if there is a wee bit left, I'll spin that out into the tray when I prime it up with the next batch of powder.

Unless you are making a straight transition between powders... with no test drops of any kind... I don't see any danger.

I get every kernel out of my drop and trickler, not out of fear but because I'm a cheap old basturd who doesn't wanna waste any of this expensive powder

I think Charlie has reasoned it out correctly. I also think you're wise to continue avoiding any cross contamination. I understand your question, "how much is too much" and I'm guessing that there are too many variables to get a real answer.

I will say with certainty that with any level of due diligence it will pale in comparison to filling a 300 win mag with h110 vise h1000. I'm positive it's been done....

AJC1 said:

I will say with certainty that with any level of due diligence it will pale in comparison to filling a 300 win mag with h110 vise h1000. I'm positive it's been done....

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What kind of velocity do you get out of your bolt?

I use a Hornady electronic dispenser and when I’m done I open the valve and pour the remains back into the bottle, then use a detail paintbrush to sweep the nooks n crannies down to the bottom then pour that back in the bottle, the pan blow compressed air in to make sure I didn’t miss any. Not necessarily to ensure I don’t mix any, I’m just that cheap, but Id bet a couple grains in a few ounces probably wouldn’t be noticed.

I’d figure it’s somewhat relative and in a forgiving direction. A few stray flakes of 700X or Tightgroup mixed in a 50gr 30-06 load is probably insignificant. A 25 or 32 auto is less forgiving in volume, but usually loaded with fast-burning powders, so a single log of IMR 3031 isn’t going to blow things up either (slow rifle powders may be ejected out of the muzzle before fully burned).
Now, larger quantities are potentially big trouble. A few grains of fast pistol powder blended in a rifle load could put you over the edge.

I am rite there with Charlie98 and his thinking. This approach has worked well for me for decades. As far as to how much you need to make a difference, it depends on the speed of both propellants and the amount of each. Not being an expert on the subject my guess is that a 1% contamination would yeild a noticable difference in small volumes. The larger the volume the larger the amount you need to notice. Note, this is a guess and do not reccomend trying to mix propellants. There is a reason we no longer load with duplex loads folks! Safety first.

lightman said:

I understand your question, "how much is too much" and I'm guessing that there are too many variables to get a real answer.

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barnfrog said:

It just makes me wonder how much adulteration it takes to make a noticeable difference, whether from spillage, erroneously and unknowingly dumping powder back into the wrong jug, or any other cause you can think of.

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Looking back at the OP, I see what you are asking... but as John mentions, the combination of factors is almost endless. Fast in to slow, slow into fast, big cartridge (.45-70) or small (9mm,) and then the percentages... 1% Unique into 45grn of IMR4895, or 1% of IMR4895 into 8.5grn of Unique? ...or 2% ...etc. As TMD mentions, slower rifle powders, for example, might not even burn well enough to make a difference in a .38SPC case at 10K PSI... and it seems like it would take a fair bit of something like W231, TiteGroup, Unique, or even W296, in a rifle charge of IMR4895 to make a significant difference. Certainly an interesting question, though.

When getting into the hot pistol powders like Clays it becomes important.

I shoot a lot of pulled cases. (I have decided that priming is for chumps) Anyway, when Speer, Federal, etc. do their self defense loads they use a tar sealant that gets powder kernels stuck to it. I load as I normally would and I don't worry about whatever unknown powder kernels may be stuck in the casing. I've loaded tens of thousands that way and never had an issue. So, not only am I mixing powders, I'm also adding a little to my charge. I probably wouldn't do it if I was trying to run max loads or over max but for a normal load, it doesn't make enough difference to cause any issues. I am the kind of guy who tries stuff just to see what it will do. I can't tell you how many damaged cases in several different ways I've fired over the years. It keeps the job interesting for me. I like learning.

I try to get everything out before switching powders, but I'm not anal about it (I'm not calling anyone anal BTW). If I leave a grain or two of powder its not going to affect the next load at all. That's grain as in spec of powder, not a grain as a measurement.

I have multiple tricklers I use with my single stage.

Been inverting the case charger from the Dillon, holding it over a funnel in the powder bottle, and treating it to a big puff of air. I have powder sticking to the plastic through static electricity, which my older reservoir did not.
The good news, if I'm changing powder, I'll be changing the charge bar as well...anything hiding will come out.
Felt a little guilty today, mixing old Unique with a new bottle, but powder is too damned expensive to waste any.
Moon

barnfrog said:

At what point does mixing powders, intentional or not, become dangerous?

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Its already dangerous or kids would still be playing with gun powder like we did when I was a kid.

The question you should ask yourself is, how far off ""the beaten path" do you want to risk traveling? Unknowns are, well, unknown...

Well, a good question, and food for thought. But so is the margin for error when pulling on the pump handle (UniFlow) 100 times for pistol cases. Sure, you get your set-up charge as close to perfect as you can, and maybe cross-check every 10th load or so for consistency, but when you are dealing with minuscule loads like my .380 at 3.5gr Unique (flake powder}, I have several times weighed that 10th charge and found it to be +/- .3gr...which can make a big difference depending on bullet, crimp and primer substitutions. I'm not desperate enough to drive myself bats**t by weighing each pistol charge on the digital scale. Same goes for leftover residual powder. Pull the pump lever until nothing else comes out and call it good.
This is not to say that for near-max rifle loads I won't weigh each one on the digital scale and trickle up as needed to make it perfect, because I do. But that's a different cat to skin altogether.

I routinely go from loading HP-38 into 9mm to loading Winchester 748 into .223.

When I switch powders, I always shake the powder measure and the powder trickler to make sure they are empty, but I don’t go any farther in trying to clean powder from them. I think that is adequate as my chronograph results from 223 following loading 9mm do not differ materially from one batch of 223 to another.

Have a 1/2 full quart jar of mistakes from not emptying powder immediately. It's like bill paying. Immediately open it upon receipt, make out check and mail it immediately. Or it can get forgotten. Am quilty of rapping on the powder measure to empty it, but do not unmount or disassemble.

I always remove the powder drop from it's mounting, pour out the powder, and operate the mechanism a couple of times till all the powder is out. Not OCD about it, but I have noticed a couple of my powders look the same but with different burn rates.

On the edge of the topic I guess, but...

I once spilled maybe a half ounce of Reloader #7 on my cluttered work bench. Lots of fine sawdust and steel filings for contaminants. Powder is too valuable to waste if it can be saved so I swept the mix into a small wooden box. then poured it into another box while blowing on it. A couple or three pours and all the sawdust was gone. Then I swished a magnet in the remaining mix, cleaned the filings off the magnet and repeated until I didn't get any more filings.
By that time the powder had no visible contaminants and no more filings. I poured it back in its original bottle and have not noticed any change in performance.

I expect some of you are horrified.

Was due to switch my measure over and remembered this thread so I performed a test, probably in worse case conditions. Conditions dry with healthy static potential as measured by petting the dog and cat. Measure is an older (roughly 15 years) Lee PP with significant hours on it. Was dialed for a 25ish grain charge of H335, which is a fine grained spheroid powder that has a tendency to leak around the edges.

I shut the powder off by rotating the hopper, then racked charges into a pan until readily noticeable drops of powder ceased. I then emptied the hopper, tapping vigorously on a board to dislodge any static cling particles. Visual check revealed none. I then actuated anything that moves, dropping into the pan until not a single kernel was noticed dropping into the pan anymore, about 30 "throws". I was able to shake 1.2-1.3 grains of H335 from an "empty" measure!!!!

Now, going to a similar burn or faster application, even if that 1.2 grains came all at once, from a safety standpoint would be a non-issue. It would certainly ruin your day in a BR or Bullseye match though. It might be serious bad JuJu to go from a fast spherical such as Titegroup to say..IMR 4350 in a relatively small case such as 6.5CM and have 1.2 grains of Titegroup in the mix!

I am reasonably certain this is exactly what happened to me when a single specimen of M1 Garand ammunition pierced a primer. Was a light load, at 46 GR IMR 4064 with a 168, scaled charges. I had immediately prior been loading HP-38. I have since instituted tighter controls to prevent any cross contamination.

I also remember reading somewhere, that fast burning powders even in small quantity can have a synergistic effect on slower burning stick or IMR types. I believe this is why Bullseye and Unique still carry a Milspec designation, for use as accelerants in artillery charges. Perhaps even a very small by proportion amount of a fast powder could have a very disproportionate result.