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Vince is one of the founders of Target Shooter magazine and, in addition to his role as editor, he is an accomplished gunsmith and benchrest shooter, having represented his country at World & European level as part of the GB Team on many occasions.


Presently, shooting is under threat from many directions – rising costs and availability of components plus the impending lead ban, to name but three. We are all becoming a little more aware of shortages and costs and maybe we are rummaging around in our reloading rooms for part boxes of bullets, old tubs of powder and getting the maximum reloads out of our brass. Here, our favourite reloading guru takes a look at powder life – something I hadn’t considered – Ed.

Taking a break from Reach-compliant powder options, here’s a related topic – powder life, and recognising when it has ‘gone bad’? These are recurring topics in powder manufacturers’ Q&As and, given recent shortages and significant price increases, on shooters’ Internet forums too. The latter is often in the form of: “I’ve been given some old tins of [whatever] – can I use them?”

Good to go – or gone bad?

What do manufacturers say? Here’s Vihtavuori’s response:

The estimated shelf-life of Vihtavuori gun powders is a minimum of 10 years, if stored and sealed in its original containers at a temperature of circa 20°C/ 68°F and a relative humidity of 55-65 %.

That leaves as much unanswered as not. Does it become unusable on its 11th birthday? What, if like most people in the UK, you don’t have a temperature and humidity controlled and monitored storage area? – I’ve no idea what the humidity is in my house and how much it varies. Does opening the bottle, partial decanting, and return of unused product, as is the norm for most people loading small batches of cartridges, affect powder condition and life? Do single and double-based powders have different life expectations; likewise tubular vs ball-type powders?

Viht goes on to say:

DO NOT KEEP OLD OR SALVAGED POWDERS. Check old powders for deterioration regularly. Destroy deteriorated powders immediately. [Upper case lettering in the original Viht wording]

……….. so as in the “… hole in my bucket, dear Liza” song, the circle takes us back to definitions of ‘old’. Ten years and a month and chuck it out, or what? (On this basis, I’m in trouble as a regular user of old lots, regularly loading 284 Win with 03.09.2004 dated Viht N165 for instance.) Personal experience aside, accounts of American handloaders using original Hodgdon supplied WW2 era surplus 4831 and similar regularly appear in the US shooting press and forums and, here in the UK, old battleship-grey painted ICI Nobel steel cans of powder from the 1980s still turn up; their contents are often fine to load if the tins are sealed and in good condition. Incidentally, those ‘surplus’ 4831 users breach both parts of Viht’s upper case stressed advice – old and salvaged (from WW2 20mm Oerlikon AA cannon shells before repackaging and sale by Hodgdon, albeit I’m sure Vihtavuori is using the word ‘salvaged’ in a very different context here).

Mentioning Hodgdon, what does this company say?

Under proper storage, modern smokeless powder can last for decades. However, this does not mean the reloader can ignore how the powder is stored, particularly if in an uncontrolled environment such as a garage or storage building.

Hodgdon explains that powder breakdown is caused by residual acids from the manufacturing process. Stabilisers are added to neutralise these compounds, but become saturated eventually and powder decomposition then starts. The key factor in how long stabilisers remain effective is storage temperature.

The entire stabilizer / decomposition process is a time and temperature function – the higher the temperature, the shorter the safe life of the powder. Even moderate temperature, over extended time, leads to propellant decomposition. As a rule of thumb, any temperature over that which is comfortable to a person is accelerating the decomposition of smokeless propellants.

So, the message appears to be that we shouldn’t take some of the more restrictive advice too literally, as huge variations in powder life occur in practice, and there are many factors involved, but keep your powders in a cool, dry place out of sunlight.

Battered Tins

Moving onto identifying problems, let’s start with the container. Common sense dictates that corroded, rusty, colour-faded, bent, battered, however abused tins, are probably indicators of extreme age and poor storage conditions, therefore best junked. The container type is also often a pointer to the product’s age. Painted steel cans and stiff cardboard-tube type containers started to be replaced by high-density opaque polymer bottles and paper labels by ‘plastic’ equivalents over 30 years ago, although some companies continued to use steel cans into the early years of this century. Hodgdon continued with tinned-steel lids for many years with its polymer bottles, but plastic screw-caps are now the norm. These materials are more resistant to temperature, moisture, and light induced changes than their predecessors, so are less likely to show abuse.

The container’s external appearance can change from the effects of powder breakdown working from the inside out, some very corrosive chemicals having been created. I read of a case where a powder can’s plastic cap was bleached from its original blue to white in this way. Before rushing out to junk Viht powders whose caps have apparently faded, note the company rebranded its products quite recently, changing the label design and cap colour.

The photograph of Viht powder bottle caps shows the much lighter blue used by the company for many years against a newer dark-blue example, so the difference has nothing to do with any potentially sinister external or internally induced change. (Actually, I wish Viht hadn’t made that change – the older model was ideal for writing the grade and date on with a permanent black marker pen.)

Would you use this?

Coincidentally, while writing this piece, a shooter from Pennsylvania put up a photograph of a can of Winchester 760 powder in a very sorry state on a Facebook reloading group page with the caption: “Ok guy’s [sic] any idea what would cause this?” Disaster had struck two tins of 760 kept in a cabinet with dehumidifier rods; 18 bottles of other grades alongside were fine. This was apparently a result of the contents having broken down and corroded the steel lid from the inside rather than external rusting from moisture in the air.

Nasty Niffs

Smell and appearance are the primary indicators of powder condition and should be checked every time you use a powder. Are there signs of physical changes to or breakdown of the kernels, the latter sometimes producing ‘dust’? Do kernels have a sticky appearance, have formed clumps, won’t flow freely? Put simply, any noticeable change at all to the powder from its fresh condition is a very bad sign! Smell the contents as soon as you open the bottle before decanting any. The smell varies across makes and types, (Viht’s N100 and 500 powders are quite different from each other in my experience) but should range from nil or nearly no smell through to a fairly strong, but not unpleasant aroma of solvents like ether and acetone. What it shouldn’t, mustn’t ever, smell of is anything like ammonia, sour vinegar, or have an unpleasant sharp, acrid tang. If you smell your usual brands every time you open the can, you should instinctively notice ‘something off’ should something change for the worse. Sometimes, decomposition produces gases resulting in a small pressure release when the cap is unscrewed, reportedly with red, or rust-coloured (probably nitric oxide) fumes visible in some instances, although thankfully I’ve never encountered this. Returning to the corroded W760 tins on Facebook, the owner responded to queries that the powder was ‘clumping’ and there was a strong ‘unpleasant ammonia smell’, pretty much as expected.

A Salutary Tale

The prompt for this piece is an old steel tin of IMR-3031. The container tells us it predates 2003 when Hodgdon Powder Co. bought IMR and changed the packaging to its standard black polymer bottle. I don’t remember when or where I bought it, but it has been kept in benign conditions throughout my ownership and the can is both internally and externally pristine. Visual inspection ticked the ‘looks OK’ box and the sniff-test produced a very mild smell, nothing unpleasant or out of the ordinary. So off I go and load some 308 Win test batches. Everything in the session is unexceptional until I finish powder charging / bullet seating and have returned the unused powder in the dispenser to the tin via the drain cock and a polystyrene funnel.

To my horror, the RCBS Chargemaster’s drain channel has some sort of reddish-brown coating, as does the inside of the machine and the powder hopper. Very thin and light, just like a household dust coating that wipes off under a fingertip. The poly funnel is the same down one side where the powder flowed. As my practice is to seat a bullet in the previously charged case while the Chargemaster dispenses the next, that was 25 rounds to pull as well as cleaning everything the powder had touched. Alongside the wasted time and effort, that’s a pound of IMR-3031 lost, an excellent, very flexible propellant that is no longer available thanks to REACH.

White Paper Test

This experience shook me as the eyeball and smell-tests had failed to show any problems, and led me to do some online research. It seems that I’m not the first so caught out, and a number of American shooting forum members mentioned an additional, allegedly reliable test to check out very old powders. Pour some powder onto a piece of clean white paper, agitate the kernels a bit, then pour them back into the powder bottle. If the powder is starting to break down and produce ‘dust’, it will stick to the paper and be more visible than when mixed up with kernels. Ignore the odd ‘sparkle’ from the shiny graphite coating applied during manufacture. There is no need for this test with your five year old powder, likely 15-year old either, but it is worth considering with very elderly lots and/or old tins with unknown histories. Well, I tried this method with the 3031 – and it didn’t work for me, not a trace of ‘dust’. It did show up lightly when poured through a clean poly funnel. I reckon that the powder in this tin has barely started to deteriorate – but the golden rule for powder is to throw it out if there is ANY sign of decomposition, no matter how small.

Open and Close; Open ……

I asked if the repeated opening and closing of the powder can accompanied by the two-way decanting of contents affects powder life. How often you open the tin and pour powder around obviously depends on your circumstances and the container size. If your powder comes in a 1lb (7,000gn) tin and you load .338 Lapua Magnum or suchlike, you might use the entire contents in a single loading session, two or three at the most. Conversely, a 1Kg (15,432gn) bottle of Viht N140 supplies 637 charges of my 223 Rem match load. As I usually load 50 rounds at a time, that sees the bottle uncapped, powder decanted, some 25 times before the contents are used up. (Remember the need to count a second opening when unused powder is returned to the bottle at the end of each session.)  

Every time we open the tin and pour powder, we expel some of the air inside and replace it with air from the room. This undoubtedly affects powder condition and its moisture content. Moisture is an enemy of powder life and as nitrocellulose powders are hygroscopic (pull and absorb moisture out of the air) frequent handling or and/or unnecessary exposure to the external environment shortens its life especially in humid climates. I read too that each air change displaces some of the stabilisers, thereby shortening the life of the remaining powder in the container. This is a particular issue for handloaders buying 8lb / 3.5Kg jugs. It’s often advised to decant a modest amount into an empty standard 1lb or similar powder bottle to cover a few reloading sessions while reducing the frequency of exposing the main body of powder to the air. This practice is however contrary to HSE regulations that powders must always be kept in their original containers. Viht’s advice is a little ambiguous on this:

Do not transfer the powder from an approved container into one which is not approved.

Is an old Viht, Hodgdon etc powder bottle an ‘approved container’ if clean, in good condition, clearly and permanently labelled with the parent jug’s product information, manufacturing lot and production date? I’d say so, but Viht might not and the HSE would disapprove. Reused plastic milk bottles (which I’ve seen used for this purpose) definitely fall within the unsuitable category.

Returning to my Viht N140 / 223 Rem load, should I decide to buy a 3.5Kg jug to save a bit of money, and pour the powder from this large container directly in each 50-round loading session, the statistics become: 2,232 charges; 44 loading sessions; 89 bottle openings and powder pours. Of course, if I were also using N140 in other larger cartridges, this would reduce. I’m not suggesting that powder bottles should never be opened – that rather defeats the object of the exercise – rather to be aware of the issue and mitigate its effects wherever possible. In my case, the obvious step is to load 100-round lots.

What is also important is to only pour enough powder for the loading session, immediately re-cap the powder container; use the powder measure’s or dispenser’s reservoir cap too instead of leaving the hopper open to the air; return unused powder to the manufacturer’s container as soon as dispensing/charging is finished, and double-check the cap is fully tightened at the end of the session before returning the powder bottle to storage. (These are basic safety practices, anyway.) If loading is done in a very humid environment, investment in a dehumidifier might be a good idea ……. and so on.


One of those things that surprise people is to discover that powder manufacturers include a small amount of water in their formulations / manufacturing processes. Norma gives a very detailed breakdown of the ingredients of its powders, and water content varies from 0.65 to 0.9% by weight depending on the grade. Maintaining the manufacturer’s level is important – change the amount of water, either way, and the powder performs differently, specifically its burn-rate changes. If the powder dries out, burn-rate becomes ‘faster’; if water content increases, it becomes ‘slower’. The storage environment may affect water content over time, likewise the opening/closing the tin issue and changes to the air inside especially if one’s reloading area sees either extreme of humidity.

Norma devotes over nine pages of its 2nd edition Reloading Manual to this issue with the effects of different external RH (relative humidity) levels on some of its rifle powders in a small range of cartridges using a series of RH vs Pressure or Velocity graphs. Note though, it measures the changes using cartridges not stored powders. This is because sporting, unlike military spec, cartridges are relatively poorly sealed from the outside air. Different storage humidity levels change the moisture content of their powder charges relatively quickly, the process taking around 12 months. (It will take much longer for the contents of sealed powder tins.) Water levels in new powders are based on a c. 40-60% RH range, so external environments outside of those values will see a net charge water loss or gain. Taking 308 Win loaded with Norma 203-B and a 180gn bullet, pressure varied by a significant 60 Mpa (8,700 psi) across a 20-90% RH storage environment range. With the powder’s original water content level based on 50-60% RH storage environment humidity, reducing that to c. 20% RH dried the powder charge out enough to increase pressure by c. 25 Mpa (3,600 psi) in Norma’s tests, enough to knock your load out of an accuracy node, or create pressure problems if the load was on the very maximum. This process can also occur with unused stored powders, but with containers being well sealed will take much longer or may not happen at all depending on the storage environment. Storage RH levels are much more of an issue in climates like those of North America with arid desert or semi-desert conditions in some states; very high humidity in others.

4831s and Other Fings

Most people are aware that IMR and Hodgdon brand versions of No. 4831 are not the same thing, H4831 being the slower burner of the pair and seeing heavier charges quoted for maximum loads (by just under 3gn in the 300WSM with a 200gn bullet). Less well known is that both were originally a single product, the IMR version as manufactured by Dupont, and the change took place during long-term bulk storage. DuPont Industries had manufactured the powder during WW2 for the 20mm Oerlikon cannon shell, vast numbers of such quick-firing light anti-aircraft guns mounted on warships. When Imperial Japan unexpectedly collapsed in August 1945, the US government was left with a huge stockpile of these small shells and later contracted out their de-milling and scrapping to a private company. The entrepreneurial Mr Hodgdon promptly snapped up the powder part of the proceeds.

As demand for very slow burning powders was modest back then, and there was such a large quantity, it took some quarter century to sell it all. However, both Hodgdon Powder and users noticed that MVs and pressures dropped as the powder aged, so maximum loads were increased over the years. When Dupont resumed handloading powder sales after the 1960s its ‘fresh’ IMR-4831 was now faster-burning with lower maxima quoted. As Hodgdon eventually approached the end of its surplus stock, it contracted out manufacture to ICI Nobel in Scotland, and specified the British company should duplicate the geriatric, not the original, version. Hence two 4831s ever since. The moral here is be careful with charges for elderly powders even if they prove to be in mint condition and safe to use. (Powder companies may change their product specifications and/or suppliers too over the years, another reason for caution.)

I asked a few other questions about powder types. Norma (and as far as I can see Norma alone) avers that ball type powders have a shorter life than tubular grades. I suspect ball powder manufacturers might dispute this. There is surprisingly little information around on single-based powder life vs that of types containing nitroglycerin, but what I found was consistent in saying single-based storage life is longer. Finally, how does my 19-year-old N165 perform against fresh powder in the 284? I cannot see any difference other than maybe a tendency to need a small increase in the scope elevation setting at longer distances. Elevation consistency and groups are as good with the old powder as with new stock.