Loads, Time, and Deterioration!

[fan_of_flux]

Will a powder charge physically breakdown over time (i.e., become smaller in particle size)? I have some 556 that I loaded in the early 2000s that I can shake and hear the powder move, but I have some I loaded just a couple days ago that I cannot hear or feel nothing when shook. I pretty sure both batches are loaded with 26 grains of 748 under a 55g FMJ.

 

[NoSecondBest]

“Pretty sure” isn’t very definitive. How old was the powder when you loaded the original shells? Where were they stored and under what conditions? I have ammo here I loaded in the early 1980’s that shoots as good today as the day I loaded it (it shot great then and still does). Don’t assume all powder and ammo deteriorates the same regardless of the storage conditions. WW2 surplus powder was being sole fifty years after the war ended and it worked great. Under good conditions it may last many, many decades.

 

[fan_of_flux]

Well, it's hard to remember what I did back then. I had just bought a new 650 and loaded about 1600 rounds at the time, I think. I might just have pull one to measure and compare.

 

[44 AMP]

Why is your box of Captain Crunch or Frosted flakes not full to the top when you open it???

Same thing with powders. Over time, vibration (movement) settle the powder and your cereal inside the case / box so what was full when filled is no longer full, and there is space for it to "rattle" when you shake it.

Stick type (IMR) powders do this most noticeably but all powders do it.

This is NOT physical breakdown of the powder it is just settling of the contents.

Enough vibration, over enough time can break down the powder kernals physically, but that is a highly unlikely situation, though not impossible.

The other way powder breaks down is chemically. Civilian made powder is intentionally made to be as stable as possible, and when done right is very stable for multiple decades, possibly a century. Ammo loaded in the middle of a war might not have as long a shelf life, as certain corners get cut, intentionally.

Unless you contaminate your reloads somehow, or store them where they are exposed to high temps or extreme temperature shifts, they will last a LONG time. Possibly longer than you will.

 

[BJung]

I've seen ammo shot from boxes that looked so old that it belonged in a museum. It depends on how you store the ammo. Ammo that survived my brother's house fire is a good example. It was exposed to a lot of heat. I pulled the ammo apart for the bullets and the black powder was grey and sooty. I think that if ammo is kept in a dry cool place it'll last a long time.

 

[fan_of_flux]

I store my ammo at the bottom of my safe, so the heat factor is not a problem. I surmise that long-term settling is the culprit to my original question. It does make more sense than the particle break-down theory.

 

[jetinteriorguy]

You might want to consider getting some labels.

 

[hounddawg]

20 year old ammo would be just babies to some of the military surplus I have shot. 30 and 40 year old ammo was considered to be in it's prime

 

[Unclenick]

Fan_of_flux,

The bulk density of some powders can vary by a span of over 10% from lot-to-lot, so it isn't surprising that cartridges loaded with one lot fills the case better than another lot did. Additionally, cartridges subjected to vibration can pack their powder down some. With spherical powders like 748, the amount of packing isn't as great as it is with stick powders (the main reason they meter from a powder measure more consistently), but there is a little.

Breakdown of powder tends to cause it to get oily-looking and clump together, not get finer and looser, so breakdown is an unlikely cause of your observed effect. But, when in doubt, get a bullet puller and pull a suspect cartridge and pour the powder out onto a white sheet of paper. If it won't pour out but sticks in the case, even partially, that's sign of breakdown if the load wasn't compressed. Smell the powder for nitric acid scent (distinctive acrid odor, not to be confused with the ethyl ether solvent odor that is normal for powder). When you pour the powder into your scale's weighing pan from the paper, inspect the white paper for red dust. If you don't have clumping, acrid smell, or red dust, the powder is not experiencing gross deterioration. The scale will confirm or deny your remembered charge weight.

The next thing I would do is reload the same cartridge, lowering the charge to a minimum starting charge, and fire one round to confirm its velocity is lower than your new rounds. You need a chronograph for that, but you can also get a sense of recoil feel and look at the primer for more rounding and so on.

There is one breakdown scenario in which deterrents break down first, increasing the powder's burn rate. It is improbable you have that based on the lack of other signs, but an abundance of caution is justified with ammunition preparation. If you have a chronograph, you can compare your old load to new loads and confirm the old one's average velocity is not more than a percent or so higher on average. This approximation for a rifle keeps you close to SAAMI guidelines for a pressure increase in aging ammo. Of course, you also have lot-to-lot powder variation, which can also make a 1% difference, but this gives you a sense of where things stand. If your velocity changed much you may move off a favorite load sweet spot anyway, in which case you may want to pull the other bullets just to adust their charge weight.

 

[T. O'Heir]

Longevity is mostly about how the stuff was stored. Heat is just one issue but it's more about variations in temperature. Changes in humidity matter too.
Like Nick says, gun powders are changed by the makers over time. The "particles" don't break down without help either.
"...some of the military surplus I have shot...." Yep. The absolute best .303 Ball I ever fired was 40 some years old when I shot it.

 

[Paul B.]

I have some FA17 .45 ACP ammo in the original 20 round box. I also had a few loose rounds of that same ammo I loaded them into a 1911 and guess what? Every one of those round not only went bang but made a decent group at 25 yards. I don't how that stuff was stored before I got it but that ammo was about 98 years old when I shot it and what I have left is 103 years old.
Interesting fact. The load was a 230 gr. hardball with Bullseye powder. Said so right on the box. I've since read the charge was 5.0 gr. of Bullseye.

I do have some .270 ammo I loaded up with one of the 4831s. I forget which but it was around 1973. About a year ago I shot some over the chronograph and accuracy tested at the same time. Chronograph data match what they tested out to back in 1980/81 and accuracy was unchanged. Those loads were stored in my house so no radical temperature changes.
Paul B.

 

[hounddawg]

The absolute best .303 Ball I ever fired was 40 some years old when I shot it.

Might be the same stuff I was thinking about in my first post on this thread. Bought a Enfield and 45 or 50 rounds of ammo mail order from an ad in the back of a magazine. I would have been 15 at the time, paid 20 bucks for th erifle 3 for the ammo and 4 or so USPS shipping. All of it was less than 30 dollars

 

[greentick]

Will a powder charge physically breakdown over time (i.e., become smaller in particle size)? I have some 556 that I loaded in the early 2000s that I can shake and hear the powder move, but I have some I loaded just a couple days ago that I cannot hear or feel nothing when shook. I pretty sure both batches are loaded with 26 grains of 748 under a 55g FMJ.

Pull the bullet and examine the powder, even just for curiosity sake.

 

[big al hunter]

I was given a box of ammunition that my FIL purchased at a yard sale. He ended up with a pile of boxes in many calibers. Some for guns he has, some he doesn't. The box he gave me is an old 20 round Winchester Western 30-06. When I looked the box over carefully I found a faded note that listed an IMR 4831 charge and a bullet weight of 180 gr. Loaded 1982, 2nd reload. I pulled them apart for the bullets and cases. The powder looked and smelled exactly as it should. No deterioration.

Your ammo should be the same. Only one way to find out

 

[Bart B.]

The other way powder breaks down is chemically. Civilian made powder is intentionally made to be as stable as possible, and when done right is very stable for multiple decades, possibly a century. Ammo loaded in the middle of a war might not have as long a shelf life, as certain corners get cut, intentionally.

As far as I know, arsenals have always used commercial powders because they don't make powder for small arms. They make their own cases and primers. They make their own service bullets. Match bullets are sometimes commercial ones.

Every mil-spec small arms ammo data I've seen lists commercial powder. Sometimes it's made just for arsenals.

The US Navy had a powder making factory in Indian Head, MD, making powder for large shipboard guns.

 

[Unclenick]

Military powder is made in the same plants that commercial powder is. I asked Hodgdon one time if they get special formulations of the spherical powders they get from St. Marks, but they said they order the exact same chemistry the powders had when they were developed for the military originally. The main difference is the military uses the bulk grade of those formulations, while the canister grade powder sold to reloaders is held to a tighter burn rate tolerance by blending with held-back older lots of the same powder type that happened to turn out faster or slower (whichever is needed) to adjust the burn rate of new lots to be closer to a nominal value.

The reason for the blending is simple. Handloaders use book data, where commercial loaders have pressure test guns they can use to adjust a load or to reject a particular lot for a particular application if the right pressures can't be reached with quantities that fit in the case well. Book data is wide enough to let you work up through a burn rate variation of ±3-5%, but bulk powder can vary by over three times that, so recipes not developed for the particular lot can't be counted on to be safe with it.

The blending practice keeps book loads usable, but it also has the drawback that you don't know how old the oldest powder blended into your lot might be. So it doesn't have just one age. As a result, every once in a while you get premature breakdown in a lot of powder and the warning notices come out.

Europeans seem to be more concerned with breakdown. Norma guarantees its powders for at least 10 years after the date of purchase, so they are tracking the age of what they blend in. Our domestic makers don't lay down an expectation limit like that. The military generally will allow munitions using single-base powders to be stockpiled until the powder is 45 years old and double-base is limited to 20 years. But figure those are minimum lifespans for single-lot (unblinded) powders, not maximums. A lot of that ammo is pulled down or surpluses
d out and then pulled down and sold as surplus and it still works fine for a long time afterward.

What allows deterioration is the powder using up its stabilizer. This is an acid-scavenging material included in the powder formulation to get acid radicals released when a molecule of nitrocellulose breaks down spontaneously (something that goes on randomly here and there all the time). If it isn't scavenged, the acid radical causes breakdown in still other molecules, gradually causing an exponential chain breakdown that destroys the whole container of powder. You see this in deteriorating surplus ammo. One round will go bad, then another, etc. They don't all go at once because of the random nature of the breakdown.