Powder storage warnings

Via email from Roger W. we have this from Hodgdon:

Powder Storage in Reloader Hoppers

Powder left in the reloader’s powder measure hoppers for extended periods, overnight or several days, should be avoided. Powder needs to be stored in original containers ONLY, when not in use. Numerous modern smokeless powders are double base in construction, containing both Nitrocellulose and Nitroglycerine.

Roger sent them an email questioned them on this (“Why not leave powder in powder measure hoppers for extended periods?”) and got the following reply:

There are a couple reasons.

Despite warning some people have multiple powders on their bench, they leave the powder in the hopper for long period of times and they forget or think they know which powder is in the hopper, they pour it back into the wrong canister and there will be a problem. this may seem like common sense but we see this happen every week from a phone call or an email.

Some powders that are made today have a very high Nitroglycerin content to them, when left in  powder measures for a period of time the Nitro will seem to eat the plastic. We have seen this with standard hand thrown powder measures and electronic ones that will get ruined.

Powder has a built in moisture content to it. the proper storage of powder is in the canister with the lid shut tight, this will help keep the moisture in the powder. Most likely there would not be a problem with moisture left in a hopper unless the lid is accidently not put back on.

Mike Van Dyke
Customer Service Representative
Hodgdon Powder Company
6430 Vista Drive
Shawnee, Ks. 66218
913-362-9455 Ext. 109

I have plastic powder measures that are yellowed and I attributed it to an interaction with the powder. But I have never seen any that appear to have been eaten. Still, I probably should be more careful about leaving the powder in the measure for extended periods of time.

11 thoughts on “Powder storage warnings

  1. They’re mixing their reasons there. Either the reason not to store power in the hopper is because it might eat the plastic, OR it’s because they deem us too stupid to label our hoppers. If they want to warn us effectively, they should not be mixing the warnings together.

    Also a general statement about “plastic” seems to me to indicate ignorance, being that “plastic” can consist of any of a wide range of materials. Are we talking about polystyrene? Polycarbonate? HDPP? I think we should be hearing about this possible chemical reaction issue from the powder makers and the makers of the powder hoppers, and the two should be getting together.

    We buy the complete cartridge conversion kits with tool hands and measure specifically so we don’t have to be handling things all the time. Dumping out the powder not only involves what should be unnecessary additional transferring of powders (introducing a greater chance of making a mistake) it’s also a pain in the ass.

    Labeling your hopper is the obvious solution to the issue of forgetting what’s in it. I figured that out all by myself, years ago, as in the day I started reloading. If I change out powder types, the label comes off the hopper and goes onto the factory container for later use, and a different label goes onto the hopper. What’s not to get?

    I have at one measure with a hopper on it that is decades old (an old friend got it used, and he later gave it to us) and the “plastic” still looks pretty good.

    Since powder has an obvious smell to it, obviously there are volatiles in it. I have attributed most of that to solvents of some kind, probably alcohol(s). If the container or hopper is not perfectly air tight, you’re losing volatiles. If you open and close the same, perfectly airtight container several times, as the powder gets used up over several sessions, you’re still losing volatiles. If yr loaded cartridges are not perfectly airtight, you’re loosing volatiles no matter how the powder was stored before being loaded into cartridges. So are we saying our ammo has a limited shelf life then?

    Sorry; I’ve heard a lot of dumb crap circulated for years, or decades even, which was simply wrong. These two, or however many separate warnings we’re getting here, have a certain oder about them, which indicate that someone hasn’t really done their homework quite enough to be going public with it.

    So I’ll take the chemical reaction with “plastic” myth, and the volatiles thing, as “preliminary warnings” which obviously call for further, multiple investigations and later clarifications based on those investigations.

    We need to know, and more importantly the powder hopper manufacturers need to know, exactly which “plastics” we’re talking about. Stop using that plastic and that issue is gone.

    We would also need to know the difference in performance between new power and a “dried out” powder. If our powders need to kept “humidified” with some specific volatile in order to perform to spec, then why have we not been warned about this terribly important issue since the 1890s? And what exact differences in performance can we expect, between a new, “humid” powder and a very dried out one?

    This reminds me too much of the “memory killed my NiCad battery” myth. EVERYONE “knew” this to be a critically important issue, vendors were selling battery discharging devices to ostensibly help ward off the dreaded “memory” monster, and yet in studying actual tests, we find that even the test labs had a hard time creating a “memory” phenomenon in a NiCad cell. It was almost all pure horsecrap based on the early use of NiCad batteries in communication satellites, which had **extremely regular** charge/discharge cycles. Altering the power management routine on the bird solved the issue. Other than that it was largely a hoax and/or a stupid excuse for premature battery failure, such failure made worse by over-cycling the batteries in an attempt to prevent it. There are many examples of similar silliness.

    Remember the dire warnings about “press-checking” you gun, how it would ruin the primer? Complete hogwash.

    And anyone getting a bit peeved at this point doesn’t understand the process of learning things. Call me names, and hit something, or kick the cat, and get it out of your system, and then realize that I have a point;
    A preliminary warning should be presented as such. This issue, or two, or three, or…(I lost count) raises many questions, and without acknowledging the fact that it raises questions, it is incomplete.

    • I used to have a label I put on the dispenser. Now I just have the one original container on the bench at a time. The other powder containers are on a shelf on a different wall than the reloading bench.

      Obviously it depends on the plastic. All the powder I have purchased in the last 10 years came in plastic containers.

      You would think the people selling powder handling equipment would do their homework and I suspect most of them have. As, I noted above, I have never seen any issue with the power “eating” the plastic.

      As much as anything I wanted to post this because someone I know leaves the top off of their powder dispenser, as near as I can tell, all the time. I thought it was risky but they were unconcerned and didn’t seem inclined to abide by my suggestion to keep it covered.

      • I have a very old powder measure that is clearly etched on the inside from powder residue. It’s at least 50 years old however. My “newer” (20 year old) measures don’t have any signs. I think it’s a combination of better modern plastics and older powders with more left over volatile residues.

  2. joe:

    i see no difference in the atmosphere in the can, and in a powder hopper. some difference in humidity, and moisture content in the powder.

    an article in the new issue of the hodgdon reloading manual, by jim carmichael. about a 20 lb can of 4831 dumped into a metal container. which he has had, and used for a long, long, long time. 40 or 50 years, maybe.

    he had a load. he loaded some new ammo w/ the old powder and the old recipe, and shot it in his old model 70 target rifle, and it made the same old boring small groups it has always made.

    store your powder in a cool dry place, and avoid exposing it to great heat or heat fluctuations. you should be o.k. people shoot surplus ammo 50 years or greater in age, w/ no adverse effect. some of that stuff is hardly what you would call “air tight.”

    john jay

    p.s. remember, they are your hands, and your eyeballs and ears. and, powder is still relatively cheap. sorta.

    • I’m not disputing most of that. I just think one should keep the lid on powder containers.

      My guess is that a properly crimped cartridge is airtight for normal atmospheric pressure variations.

  3. If you want to see the plastic get “attacked”, put Titegroup in your hopper and leave it for an extended period.

    • As Lyle said, if the plastic gets attacked, blame the design engineer for picking the wrong material.

  4. gunpowder will deteriorate, even when properly stored, given enough time. Decades.

    War story assumed. Used old powder and it fizzled when fired. Sealed container? No … in a powder measure (I have several set for different loads, on a rack on the back of my bench). Powder measures aren’t appropriate storage for long (years) storage. And the powder was junk I got off a prize table at a match, who knows how old? Dumped the rest of it in the toilet.

    Powder is cheap. If you have a partial powder-measure full for over a year, flush it. In a can? It’s probably good for decades. NOT A GUARANTEE!

    (Not sure? Load a few test rounds and go shoot them; always a good excuse to spend an afternoon at the range!)

  5. All explosives, including gunpowders, are based on nitrate compounds. If the compound is sufficiently reactive (which we would hope gunpowder is, else it won’t do what we bought it for), it will off-gas nitrate esters (called an oxidation-reduction reaction) continuously, from the moment of manufacture. One of the functions of stabilizing additives is to absorb these esters, preserving the powder’s potency in the doing.
    These nitrate esters can combine with humidity in the air to form nitric acid, so I suspect it is a mild form of nitric acid that is attacking your hoppers (nitric acid also stains skin yellow). If the problem were more pronounced in Seattle than in Tucson, that would tend to confirm that supposition.
    This reaction also is exothermic, meaning it gives off heat. Stored in sufficient bulk, the accumulation of nitric acid and the self-heating nature of the reaction can lead to spontaneous combustion. This is why the military discards all stored bulk gunpowder after a certain fixed period (IIRC, 25 years for double base powders and 40 years for single). Not because it’s losing potency but because the stabilizers in the powder could have reached their “storage capacity” (for lack of a better term) after that time, after which the rate of off-gassing will increase and, along with it, the potential for a bunker fire.
    The difference between powder sealed in the jar and powder left in the hopper is that the powder in the jar only has access to a limited amount of moisture. Once it has sucked all the water out of the air that’s inside the jar, that’s all it’s going to get. Powder left in the hopper has a far larger supply available. And it stands to reason that powder manufacturers long ago formulated a plastic for their jars that is impervious to nitric acid.
    All this absorbing of water can make powder appear to be losing it potency far faster than the natural aging process would account for. The individual granules do not swell from the water, meaning a given measure of powder will weigh heavier due to the weight of water it has absorbed. So when measured by weight, over time, you could be getting less and less gunpowder and more and more water. So a given charge weight will produce progressively less and less muzzle velocity (another reason not to keep your powder lying about loose). But the process is reversible, just add a sufficiently large packet of desiccant to the powder jar and leave it a few days. I have seen MVs jump by hundreds of fps after a few days with the desiccant, so be careful of an overpressure if you’ve adjusted charge weight to compensate for what appeared to be the powder losing its potency.

    • “All explosives, including gunpowders, are based on nitrate compounds.” Not quite. The vast majority are compounds that contain nitrogen. But they aren’t necessarily nitrates, not even if you loosely apply that term to include nitric acid esters. For example, azides aren’t, nor are fulminates. And potassium perchlorate doesn’t contain any nitrogen.

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