We’ve all heard the old adage: “Keep your powder dry.” Well, tests by Norma have demonstrated that even normal environmental differences in humidity can affect the way powders burn, at least over the long term. In the Norma Reloading Manual, Sven-Eric Johansson, head of ballistics at Nexplo/Bofors, presents a very important discussion of water vapor absorption by powder. Johansson demonstrates that the same powder will burn at different rates depending on water content.
Powders Leave the Factory with 0.5 to 1.0% Water Content
Johansson explains that, as manufactured, most powders contain 0.5 to 1% of water by weight. (The relative humidity is “equilibrated” at 40-50% during the manufacturing process to maintain this 0.5-1% moisture content). Importantly, Johansson notes that powder exposed to moist air for a long time will absorb water, causing it to burn at a slower rate. On the other hand, long-term storage in a very dry environment reduces powder moisture content, so the powder burns at a faster rate. In addition, Johansson found that single-base powders are MORE sensitive to relative humidity than are double-base powders (which contain nitroglycerine).
Tests Show Burn Rates Vary with Water Content
In his review of the Norma Manual, Fred Barker notes: “Johansson gives twelve (eye-opening) plots of the velocities and pressures obtained on firing several popular cartridges with dehydrated, normal and hydrated Norma powders (from #200 to MRP). He also gives results on loaded .30-06 and .38 Special cartridges stored for 663 to 683 days in relative humidities of 20% and 86%. So Johansson’s advice is to keep powders tightly capped in their factory containers, and to minimize their exposure to dry or humid air.”
Confirming Johansson’s findings that storage conditions can alter burn rates, Barker observes: “I have about 10 pounds of WWII 4831 powder that has been stored in dry (about 20% RH) Colorado air for more than 60 years. It now burns about like IMR 3031.”
What does this teach us? First, all powders start out with a small, but chemically important, amount of water content. Second, a powder’s water content can change over time, depending on where and how the powder is stored. Third, the water content of your powder DOES make a difference in how it burns, particularly for single-base powders. For example, over a period of time, a powder used (and then recapped) in the hot, dry Southwest will probably behave differently than the same powder used in the humid Southeast.
Reloaders are advised to keep these things in mind. If you want to maintain your powders’ “as manufactured” burn rate, it is wise to head Johannson’s recommendation to keep your powders tightly capped when you’re not actually dispensing charges and avoid exposing your powder to very dry or very humid conditions. The Norma Reloading Manual is available from Amazon.com.
Real-World Example — “Dry” H4831sc Runs Hotter
Robert Whitley agrees that the burn rate of the powder varies with the humidity it absorbs. Robert writes: “I had an 8-lb. jug of H4831SC I kept in my detached garage (it can be humid there). 43.5-44.0 gr of this was superbly accurate with the 115 Bergers out of my 6mm Super X. I got tired of bringing it in and out of the garage to my house for reloading so I brought and kept the jug in my reloading room (a dehumidified room in my house) and after a few weeks I loaded up 43.5 gr, went to a match and it shot awful. I could not figure out what was going on until I put that load back over the chronograph and figured out it was going a good bit faster than before and the load was out of the “sweet spot” (42.5 – 43.0 gr was the max I could load and keep it accurate when it was stored in less humid air). I put the jug back in the garage for a few weeks and I now am back to loading 43.5 – 44.0 gr and it shoots great again. I have seen this with other powders too.”
If you have two jugs of the same powder, one kept in a room in your house and one somewhere else where it is drier or more humid, don’t expect the two jugs of the same lot of powder to chrono the same with the same charge weights unless and until they are both stored long enough in the same place to equalize again.
Shooters rejoice — we now have new propellant options for rifles, pistols, and shotguns. Noble Sport is now importing its VECTAN series of powders, which are available now at Grafs.com. What’s even nicer, the VECTAN bottles contain 1.1 pounds of powder, so you get a little extra for your money (compared to traditional 1-pound containers). Check the VECTAN Reloading Data Page to see what Nobel Sport powders best suit your needs.
Looking for powder? Precision Reloading just received a pretty large shipment of Hodgdon, IMR, and Winchester Powders. This vendor also has popular Accurate, Alliant, Norma, and Vihtavuori Powders in stock. Sorry, no Varget or H4350 arrived, but Precision Reloading does have many popular propellants now. Powders currently IN STOCK at Precision Reloading (as of 9:00 am, 3/12/2015):
Reloading tip: If you currently use Alliant Reloder 15, Norma 203 B is very, very close. It is made by the same manufacturer, in the same plant, with the same burn rate and kernel size. Of course, for safety, you should still start low and work up your load incrementally.
Rick Jensen, Captain of the U.S. F-Open Rifle Team, recently tested some of the new IMR 4451 powder. Rick and other team members were looking for a good powder that could replace Hodgdon 4350 which is difficult to obtain currently. The makers of IMR 4451 claim that it is not sensitive to temperature and that it delivers competitive accuracy. So far, Rick’s tests, done with a .284 Winchester and 180gr Berger Hybrids, appear to confirm those claims. Rick posts:
“I did a little informal powder comparison of H4350 versus the new IMR 4451. Rifle used was a Kelbly Panda with a 30″, 1:8.75″ twist 5R Bartlein barrel [chambered in .284 Win]. All charge weights were 50.0 grains using CCI BR2 primers. I was very impressed with this new powder and I believe it to be equal to H4350 as far as temperature sensitivity.
I did not test for accuracy but I will tell you my groups were pretty much equal between the two and all were in the .2-.3 MOA range. I will defiantly be shooting more of this powder in the weeks to come, assuming the supply chain will allow. It looks very encouraging to finally have a alternative to H4350 that we might actually be able to buy.”
Chronograph Results with Temps from 23° F to 101°
Here are chronograph results of a comparison test between IMR 4451 and H4350. Rick’s rifle was cleaned and allowed to cool between each test. Five fouling shots were fired before each test. Important: Note that for both Test #1 and Test #2, the powder order is reversed in the mid-temp fields (IMR 4451 first, then H4350). For the low and high temp entries, H4350 is listed first.
Here are the IMR 4451 fired cases, displayed Left to right, coldest to the hottest (in terms of case temp when fired). All charge weights were the same: 50.0 grains.
You can never be too safe when hand-loading your own ammunition. This helpful Brownells video outlines the Seven Fundamental Reloading Safety Tips. This is important information for novice hand-loaders and a good refresher for those with reloading experience!
Summary of the Seven Safety Tips:
1. Store your reloading supplies in a safe and dry location, away from children and away from any possible source of ignition. This includes keeping your powder and primers separate.
2. Get and use respected reloading manuals, especially for new cartridges. Start low and work up slowly while watching for warning signs of pressure and/or case fatigue.
3. Locate your reloading activity where you will not be distracted. If you get interrupted, stop. (Distractions will eventually lead to mistakes.)
4. Do NOT mix powders. Keep your powders clearly marked and dated. You can use masking tape to write the date on the container.
5. If you load the same cartridge type for different firearms, make sure your ammo headspaces properly in each gun.
6. Check cases frequently. Look for split necks, case head separation or other signs of fatigue and excessive pressure.
7. If reloading military brass, be aware that case capacity is usually reduced, and initial loads should be at least 10-15% lower than published data.
Here are some other tips that will help your avoid making costly mistakes (such as using the wrong powder, or undercharging a case):
Powder Type — Always double-check the label on your powder containers. After placing powder in the powder measure, put a piece of tape on the measure with the powder type written on it. Some guys write the powder type on a card and place that right in the hopper.
Scale Drift — Electronic balances can drift. If you are using a digital powder scale, calibrate the scale with a test weight every 50 rounds or so.
Case Fill — If you throw more than one charge at a time, look INSIDE every case before seating a bullet. Squib charges can be dangerous if you don’t notice them before firing the next round.
Progressive Presses — When using a progressive press, consider using an RCBS Lock-Out Die. This will detect a low charge and stop the machine. These dies will work with RCBS, Hornady, and Dillon progressives.
We can predict, with some certainty, how long a light bulb will last (in use), or a shingle roof, or even a nuclear reactor. But how about barrels? Is there a way to reliably estimate barrel life based on known characteristics? This article explains one effort to quantify barrel life…
How long will a barrel last before the accuracy “goes south”? There are so many variables involved (powder type, bore diameter, bullet coatings etc.) that it’s hard to predict. You might say “Well, my buddy has a .243 and he got 1500 rounds before the throat was shot out” — those kind of comparisons can be useful, but they’re not very scientific, and they won’t help much if you’ve got a gun in a new chambering (such as the 6.5×47) for which long-term test results are lacking.
Is there a more reliable way to predict barrel life — one that will work for a broad range of calibers? Well, Forum member MikeCr has developed an Excel spreadsheet that accounts for a number of variables, and gives a pretty good estimate of useful barrel life, whether you’re shooting a .223 Rem or a 338 Lapua Magnum. Mike’s program predicts barrel life using five variables: 1) Bullet Diameter; 2) Powder Charge weight; 3) Powder Heat Potential (KJ/kg); 4) Pressure (in psi); and 5) Bullet Coating (yes/no). Mike provides a table with Heat Potential ratings for most popular powder types. The user needs to know the pressure of his load. This can be estimated with QuickLOAD.
You can download the lastest version of Mike’s spreadsheet below. You’ll need Excel or an Excel viewer to open the file.
Shown below is Mike’s Spreadsheet, with variables for a 6BR shooting 105gr “naked” bullets with 30.3 grains of Hodgdon Varget powder. The formula predicts 2401 rounds of barrel life. That corresponds pretty well to what we’d expect for a 6BR — about 2500 rounds.
Mike observes: “There has been a lot of discussion lately related to cartridge design and resulting barrel life. This is a really important factor to consider amongst a myriad of choices. Barrel life is controversial, and subjective. There are no clear-cut standards for comparison. But a few years ago, I put together a spreadsheet based on Bart Bobbit’s rule of thumb. It worked pretty good, only occasionally failing some tests when validated against posted barrel lives.
According to Ken Howell, I had to account for pressure. And Henry Child’s powder temperature testing provided another piece needed. So, I’ve tweaked it here and there to pass more tests. From 223 Rem to 300 UltraMagnum. Another element added, but turned off, is shot interval. I would need way more tests to lock in on this. But everyone knows, the faster you shoot, the worse the barrel life.
Anyway, another factor hard to define is ‘accurate’ barrel life. This cannot be quantified without standards. Barrels are replaced when expectations are no longer met. I feel that a [barrel] passes peak potential in a finite period due to throat erosion. But that don’t mean it’s toast, if it still shoots well enough. It’s just as likely that many of us never see that peak potential anyway. It’s a slippery thing. Point-blank BR competitors will toss a barrel when it leaves the 1s. I could get another 4000 rounds from it, and be content with its performance, I’m sure.”
NOTE: Mike says: “This spreadsheet may show a lower barrel life than you prefer. But it pretty well spotlights cartridges to stay away from if you plan much time at the range or in dog town.”
Editor’s Comment: Mike’s spreadsheet is a helpful tool, but it is NOT a definitive “take-it-to-the-bank” indicator of barrel life. Mike cautions that predicting barrel life involves so many different factors (including how hot the barrel is run), that the task is a bit like predicting tread life on car tires. Still, the spreadsheet is very helpful. It can certainly warn us that some chamberings (such as the 6-284) are likely to be barrel burners. That can help you make a smart decision when choosing a chambering for your next rifle.
Most of us assume that if we weigh our powder carefully (down to the tenth of a grain or less) we can achieve a uniform powder fill from case to case in our handloads. Weighing does ensure that the weight of the propellant in each case is the same, but is the column of powder the same by volume each time? “Not necessarily” is the answer. An interesting experiment by our friend Boyd Allen demonstrates that the manner in which you place kernels in the case can make a significant difference in the height of the powder column within the brass case.
Using a Gempro 250 scale, Boyd measured exactly 30.6 grains of Vihtavuori N-133 powder. He then inserted this powder in the same cartridge case multiple times. (The case has a fired primer in place.) But here is the key — Boyd used various filling techniques. He did a slow fill, and a fast fill, and he also experimented with tapping and drop tubes. What Boyd discovered was that you can start with the exact same weight of powder (in fact the very same set of kernels), yet end up with vary different fill heights, depending on how you drop the kernels into the case. Look at the photos. Despite variations in lighting, the photos show the same 30.6 grains of powder, placed in the same cartridge, with four different methods.
Boyd Explains the Procedure Used for his Experiment.
EDITOR’s NOTE: So there is no misunderstanding, Boyd started with a weighed 30.6 grain charge. This identical charge was used for ALL four fills. After a fill the powder was dumped from the case into a pan which was then used for the next fill technique to be tried. So, the powder weight was constant. Indeed the exact same kernels (of constant weight and number) were used for each fill.
Boyd writes: “I used the same powder for all fills, 30.6 gr. on a GemPro 250 checked more than once. All fills employed the same RCBS green transparent plastic funnel. The fast drop with the funnel only overflowed when it was removed from the case neck, and 15 granules of powder fell on the white paper that the case was sitting on. The fast-funnel-only drop with tapping, was done with the funnel in place and the case and funnel in one hand, while tapping the case body with the index finger hard, many times (about 20 fast double taps). My idea here was to “max out” the potential of this tapping technique.
The slow drop with the funnel and 10″-long .22 cal. Harrell’s Precision drop tube, was done by holding the scale pan over the funnel and tapping the spout of the pan repeatedly on the inside of the funnel about 1/3 down from the top, with the scale pan tilted just enough so that the powder will just flow. Many taps were involved, again, to max out the technique.
Again, to be clear, after each case filling, the powder was poured from the case back into the scale pan carefully. You may notice the similarity between the fast drop with the drop tube, and the funnel only with tapping. Although I did not photograph it, fast tube drop and tapping (combined) improved on tapping alone, but only to about half as far down the neck as the slow with drop tube. Due to the endless possible permutations, I picked four and left it at that.
I believe that I can make the rough judgment that the scale pan funnel and drop tube technique, which involved a longer drop period, and probably less velocity at the top of the tube, left more room in the top of the case neck than the slow drop from the measure with the same drop tube. You have both pictures, so you can make the comparison.” — Boyd
Does Powder Column Height Variance Make a Difference?
Boyd’s experiment proves pretty conclusively that the method of dropping a given weight of powder can affect the height of the powder column in the case and the degree of powder compression (when a bullet is seated). He showed this to be true even when the exact same set of kernels (of constant weight) was used in repetitive loadings. This raises some interesting questions:
1. Will subsequent cartridge transport and handling cause the powder to settle so the variances in powder column height are diminished?
2. If significant inconsistencies in powder column height remain at time of firing, will the difference in fill level hurt accuracy, or result in a higher extreme spread in velocity?
3. Is there any advantage (beyond increased effective case capacity) for a tight (low level) fill vs. a loose (high level) fill?
We don’t know the answer to these follow up questions. This Editor guesses that, if we tested low-fill-height rounds vs. high-fill-height rounds (all with same true fill quantity by weight), we might see meaningful differences in average velocity. I would also guess that if you fired 10 rounds that exhibited quite a difference in powder column heights, you might see a higher ES/SD than if you shot 10 rounds loaded with a very consistent powder column height (either high or low). But further testing is needed to determine if these predictions are true.
Grafs.com now has many popular IMR Powders in stock (see inventory below). And, the price is right on IMR 4895 and IMR 4350 — Just $24.99 per pound with current sale pricing. Act soon, as quantities are limited. Note, for IMR 4895 and IMR 4350, customers are limited to ten (10) pounds of each propellant per order (that’s ten, 1-lb containers of each).
Midsouth Shooters Supply has received a substantial amount of popular reloading powders. This is good news for folks who have been short on powder. No, there’s still no Hodgdon Varget or H4350, but Midsouth does have many other great propellants in stock. Hodgdon powders in stock today include the popular H322, Benchmark, Retumbo, H50BMG, and US 869 (a spherical powder for big magnums). IMR propellants in stock include IMR 4227, IMR 4320, IMR 4831, IMR 4895, IMR 7828SSC, IMR 8208 XBR. Midsouth also hase Vihtavuori N135, N160, and N165 in stock now.
This holiday weekend, Grafs.com has been offering value-priced combos of powder and primers. AR guys and varmint hunters should like the combination of Hodgdon CFE223 powder and CCI 400 (small rifle) primers (item #July4combo01). This combo gives you six (6) pounds of CFE223 powder plus 5,000 CCI 400 primers for $265.99, plus a single $28.50 hazmat fee.
If you prefer Winchester powder, you can get 6 pounds of Winchester 748 powder plus 5000 CCI 400 primers for $269.99 (plus hazmat). Lastly, if you prefer to purchase by the jug, Grafs.com is offering a combo pack (item #July4combo03) with one 8-pound jug of IMR4064 plus 5,000 CCI 400 primers for $299.99 (plus hazmat). Take your pick — these are all pretty good deals.
Tests Show Burn Rates Vary with Water Content
“I did a little informal powder comparison of H4350 versus the new IMR 4451. Rifle used was a Kelbly Panda with a 30″, 1:8.75″ twist 5R Bartlein barrel [chambered in .284 Win]. All charge weights were 50.0 grains using CCI BR2 primers. I was very impressed with this new powder and I believe it to be equal to H4350 as far as temperature sensitivity.
How long will a barrel last before the accuracy “goes south”? There are so many variables involved (powder type, bore diameter, bullet coatings etc.) that it’s hard to predict. You might say “Well, my buddy has a .243 and he got 1500 rounds before the throat was shot out” — those kind of comparisons can be useful, but they’re not very scientific, and they won’t help much if you’ve got a gun in a new chambering (such as the 6.5×47) for which long-term test results are lacking.
This holiday weekend, 
