Powder shelf life, do some last longer than others?

[Shadow9mm]

Yet again the powder shelf life question. But mine if from a slightly different perspective.

Do some powders last longer that others, give the same proper storage conditions? And if so, to what is it due?

My thoughts were it could be due to the base powder itself being naturally more stable.

Or the stabilizers/preservatives. Are there different stabilizers/preservatives in use? If so are some better than others? Does the quantity of the stabilizer effect the shelf life? Does the stabilizer itself effect the way the powder burns?

 

[RoyceP]

I have some powder I bought 40+ years ago. It's fine. I think most smokeless powder is good for a very long time so long as it doesn't get too hot or contaminated by something.

 

[Paul B.]

I still have some powder I bought around 1970 something. it was about the first time I bought a rifle in .308 Win. and the powder was H335. That makes that powder 50 years old. I did some load work using it in a .35 Whelen test with 250 gr. bullets and it shot just fine.

I do think double based powder store much better than single base for whatever reason. I've never had a ball type powder go bad but I have had some stick powder spoil on me. Note that AFAIK, ball type powders are all double bases. Stick powders may or may not be double based.

I store all my powders in a couple of refrigerators out in a shed. Our summer heat can go as high as 125 degrees out on that shed. My reloading shed which is separate from the powder shed has A/C but I have to turn it off when I load ammo. The air currents affect the measuring scales badly.
Paul B.

 

[FITASC]

I still have some metal DuPont IMR powder that still works just fine

 

[Unclenick]

Shadow9mm,

The British military (the one for which I've seen the numbers published) limits the stockpile life of munitions loaded with double-base powder to 20 years and with single-base powder to 45 years. That will, of course, be worst-case conservative, and many of those powders would last longer, but it's an indication. Unfortunately, it is only a reliable indication for bulk-grade versions of a powder, such as military arsenals and large commercial manufacturers usually use. The canister-grade powders sold to reloaders must have a tighter burn rate specification than bulk powders. This is because the arsenals and large commercial loading operations (and even some small ones) have pressure test guns. They can test each bulk lot of powder they receive and adjust their loads to match the individual lot to their performance specification. But handloaders rely on recipes in books that don't magically change to match your powder lot, so the canister-grade powders for handloaders have an extra manufacturing step in which their burn rate is tested. Then they are mixed with slower or faster bulk lots of the same powder type to adjust the new lot's net burn rate down or up, as needed to achieve the tighter burn rate specification.

There are several strategies for acquiring those different bulk powder bun rates. Norma breaks each bulk lot into four batches and gives each batch a different amount of deterrent surface treatment. So they have four burning rates of the same powder every time and feel they can best arrive at matching performance in new lots by adjusting the ratios of those four. I don't know what they do with leftovers. Others use held-back previous bulk lots that were faster or slower than their target values and use those to adjust the new lot's burn rate. In this case, you don't know how old the oldest powder in your can is. It might start to break down sooner than you think if it is old enough.

If you look at the past lot recalls for different powder types, you will see these practices sometimes result in a very short life, which is unusual. Norma says they warrant powder for ten years if it is properly stored. That seems short if everything went well in the manufacturing process. Still, they don't have control over how warm it got in the shipping containers or at any other stage of the transfer from the factory to the handloader, so that is a bit of a CYA number. Because powder deterioration depends mainly on the rate of deterioration of the stabilizer in it, and that gets exponentially faster with the increase in storage temperature, I expect any powder stored in a freezer would likely outlast its owner and probably his offspring as well.

 

[Nick_C_S]

the stockpile life of munitions loaded with double-base powder to 20 years and with single-base powder to 45 years.

I'm curious why single-base propellants would receive a longer "life rating?"

I only have experience with two single-base propellants. N-310, and AA2495. The N-310 is excellent and clean burning. The AA2495, I have only loaded 12 rounds, and they ran 200 f/s below the books data. I'll resume that testing this spring. Sorry to get off track - I digress.

At any rate, single-base powders intrigue me and I would like to understand more about the single-base / double-base subject.

 

[Nick_C_S]

Shadow9mm, all I can add is my personal experience . . .

In 2014, I found partially used 1# cans of W231 and W296 at my father's house. They were stored in near-perfect room temp conditions in a linen closet since no later than 1987. I took 'em home, loaded and fired them with perfect results. 27 years, for those keeping score at home . (CCI 500, 550, 300, 350 primes too - all went bang.)

In Feb '19, I bought a 1# can of Ramshot Silhouette. First opened it in March '19. In May '22 it had turned bad and stuck a bullet in my revolver (pushed out with a wood dowel, no harm done). This powder was stored with some 30 #'s of other powders, and none of the others (so far) seem to have a problem.

Seems to be little rhyme or reason to me. I think, sometimes powder just goes bad - unscientific, I know.

 

[Unclenick]

It's a dual problem of blending with older lots, and sometimes the transport and warehousing conditions get too warm. The temperature inside a shipping container left out in the full sun in a hot location can get surprisingly high. Standard appliance design and packaging practices target the ability to tolerate 170°F because of it.

I think the reason double-base powder is less durable is that nitroglycerine, being a less stable compound than nitrocellulose, likely has a higher rate of the spontaneous decomposition of individual molecules, which puts a higher load on the powder's stabilizer supply that neutralizes the resulting nitric acid radicals. However, I am not an energetic materials chemist, so if one is out there, please chime in.

 

[Metal god]

I asked this before but don’t remember. What powders are single base and which are double base ?

Is there a list somewhere that breaks them all down into that category/s ? Why do I want to say stick are mostly double and ball are mostly single ? I get totally lost when it comes to flake or other handgun types . Like H-110 what is that ? I have more then a 20year supply of that because I don’t use it much . I’ve been trying to sell or trade it for some 2400 . If it’s going to last 45yrs I won’t sweat it as much haha

I do remember thinking I should change to all double based powders . If I recall , turned out it would be a lot harder then I thought based on what I load and how much powder I already have .

 

[Marco Califo]

Sticks are typically single base.
Ball powders are typically double based.
Deterrents are also used to influence burn speed.
"Winchester® StaBALL™ HD is a temperature-insensitive, double-base, BALL® Powder"
"Accurate 4350 Smokeless Propellant is a short cut, single-base, extruded rifle powder"
Quotes from Midsouth.

 

[GeauxTide]

I have a paper can of Unique from the 70s. Still works.

 

[Jim Watson]

Most of the Made in USA Alliant flake pistol and shotgun powders are double base but I have read that the nitroglycerine content is lower than it used to be.

Extruded double base powders like Cordite and Hi Vel No 2 were hot burning and more erosive to barrels than single base.

The Vihtavuori 500 series powders contain nitroglycerine but I once read that it is incorporated differently, not like a traditional double base.

 

[Unclenick]

The easy way to distinguish one from the other is to look at the MSDS. If nitroglycerine is listed, it is double-base. There are also triple-base powders and double-base using something other than nitroglycerine that I've read about, but all are for military applications, AFAIK.

I've never seen double-base powders sold for handloading that used anything but nitroglycerine. It is mainly used to increase powder energy density. Nitrocellulose comes out of manufacturing as mainly nitrocellulose hexanitrate, but there is usually some portion of the tetranitrate and mononitrate molecules in with it. All of them have what is called a negative oxygen balance. That means that when they burn, they don't produce enough oxygen to burn up all of the fuel molecules (carbon, hydrogen, nitrogen) that are released along with the oxygen during combustion. Nitroglycerine, on the other hand, has a small positive oxygen balance, releasing about 3% more oxygen than it needs to burn its fuel molecules, and that would make up about a 7th of the nitrocellulose shortage if the percentages were 50:50, but, obviously varies proportionally to the mix ratio. A list of the oxygen shortages and excess is below.