Powder speed

How can you tell? Check your reloading manual. If a powder is not listed for your cartridge and bullet weight, then it is too slow or too fast for that cartridge and bullet weight. (Or the developers didn't find it worked well for some other reason.)

The manuals will give you a set of powders that the companies who write the manuals have found produce good results in a given cartridge. If the loads you're using are in the book(s), then the powders are neither too fast nor too slow for your cartridge.

If you go look up a burn rate chart you'll see that those powders will be ranked as faster or slower relative to each other. But that information isn't really actionable. It really doesn't matter.

In the burn rate charts there are hints and clues as to what powders MIGHT be a good thing to try in a cartridge a wildcatter is working up, or if you're super experienced and want to risk your gun and fingers by playing outside of the book recipes. (DON'T DO THAT.)

Again, if the loads you're using are in the book(s), then the powders are neither too fast nor too slow for your cartridge.

First thing that matters is safety. (So stick to the book values.)

Second thing that matters is accuracy. Only hits on paper will tell you that. Make up some rounds and test them. Pick the loads that shoot most accurately in your gun.

Third thing that matters is velocity. IF you have a number of loads that all seem to be equally accurate, you might decide to pick the one that pushes the bullet fastest, when you shoot over a chronograph. (Because that will give you a slightly shorter flight time to the target, and thus a "flatter" trajectory. More forgiving of range estimation errors. By a tiny bit.)

Fourth thing that might matter is standard deviation of your velocities. IF you have several loads that are equally accurate, and IF several of those all produce about the same velocity, then maybe you might choose a favorite by which one's velocities are the most consistent.

No where in that list is burn rate found. If you work through that list and are happy with the results you're getting, there's no reason to worry about burn rate.

Now, having gotten the most important stuff out of the way, some more insight:

There is a general trend, when you look across a large collection of cartridges and bullet weights to see that smaller cartridges with lighter bullets tend to like powders on the faster end of the spectrum and large volume cartridges and heavier bullets tend to appreciate slower burning powders. Mostly because of not wanting to spike pressures too high as the burning propellant starts to move the large heavy mass of bullet and remaining powder charge down the barrel. More of a shove than a smack. But this is heavily modified by cartridge shape. Straighter walled cartridges with little or no bottle-neck tend to want faster burning powders and more necked-down style cartridges want slower ones. Sort of.

Kind of. More or less.

None of that is "data" you can use to make smart decisions about your loads. They're just observations about the trends in the data that load developers have compiled seem to generally follow.

Read the manuals, make up a variety of test loads, go shoot and record your results. Pick the most promising loads based on those results and then play with increases and decreases in charge weight, bullet, seating depth, primers, etc. You may eventually discover that the loads your rifle likes best use the "fastest" powders listed for that cartridge and bullet weight. Or the "slowest", or something in the middle. Don't worry about that. It doesn't matter.

Amen to Samm1911, On the money...

Dan

Well, I'll just add... nuttin'

muleman11 said:

How can you tell if the powder you are using in your rifle is too fast or too slow? What are the signs to look for ?

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When the powder is too fast you'll reach maximum pressures at a relatively low velocity. A chronograph helps understand what's happening. If you are working with a cartridge that is capable of say 2,500fps with the bullet weight you are using given an optimum powder choice, if the powder is too fast you'll reach maximum pressures below that speed. You might find that when you load enough to produce 2,200fps the primers are cratered or pierced, extraction is difficult, case head expansion can be measured as execessive, and so on.

If the powder is too slow you will also be unable to reach the velocities achieved by a optimum powder choice. But things will play out differently, with no pressure signs and likely evidence of an incomplete burn. Black fouling and even unburned powder shards may be noticeable.

As others are pointing out, there is a substantial amount of published data that can help you decide what powders are suitable for your application without testing for that specific variable. When new to reloading it's best to stick with reloading components for which solid published data exists to improve the chances that in your case things will work out roughly as the data indicates, and you'll be able to achieve useful velocities and accuracy without producing dangerous chamber pressures.

muleman11 said:

..... How can you tell if XYZ powder is too fast or too slow, in order to move to a faster or slower burn?

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By trying them in your firearm. All of them. With different projectiles, and different charge weights.

You find the best by trial and error.

This is what we do.

While I'm not as experienced as some here, if a powder is listed, and charges kept within the recommended "window" you will be safe in trying that powder as they are neither "too fast" nor "too slow" for that particular cartridge. The way to determine a "good" powder for your gun is trial and error. If you have a chrony, use that to see which powder is most efficient, and I most often just use accuracy as a guideline...

Perhaps after another 20 years of study I can give a better answer, but for my "semi-advanced" experience this is what fits my reloading knowledge...

What I meant is that there are over 20 powders listed in manuals for a given cartridge. I am reading on here that XYZ powder may be too fast or too slow and better results my come from changing to ABC powder. How can you tell if XYZ powder is too fast or too slow, in order to move to a faster or slower burn?

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Well, in all seriousness, do not get hung up on people's statements that this or that powder is too slow or too fast. It's an incomplete picture of what's going on and gets you concentrating on things that aren't really first, second, or third in line for developing safe and well-performing loads.


HOWEVER, there is a real big clue in the reloading manuals as to how you can try to optimize that factor if it really gets stuck in your head.
In your manual, find the cartridge you're shooting and then the bullet weight you want to use. Under that bullet weight will be listed a variety of powders with their range of appropriate charge weights and expected velocities. Some of the powders listed will be shown as producing a spread of velocities that's faster than others.

Look at Nosler's page on the .308, with 110 gr. bullets: https://load-data.nosler.com/load-data/308-winchester/
I like how they present their velocity data in a bar graph so you can quickly see which powders produced the highest velocities.

Those one or two powders producing the best velocities (in this case, Benchmark and 8208 XBR) are probably, more or less, those with the most optimum burn speed for the cartridge, bullet weight, and gun they were shooting.

Now click on the tab to look at the same cartridge, firing 190 gr. bullets. There's a totally different set of powders listed. Benchmark and 8208 aren't even on the list anymore! Now the best performers are W760 and 2000-MR (which, honestly, I've never heard off). Benchmark and 8208 would be too ... something ... for that case volume, case shape, and bullet weight. Probably you could sum it up as "too fast" if you wanted. Their peak pressure probably comes too soon and doesn't give that much heavier bullet enough micro-milli-seconds to start getting out of the way before pressure is too high.

All that to say, at whatever bullet weight, the powders that are in the top two or four choices for providing the highest velocities will probably be those where you'll find good success with accurate loads and optimized velocity numbers.

That doesn't at all mean that they're going to be the most accurate in your gun. But if you want to narrow things down as you begin your search, that's a fine place to start.

Keep in mind when thinking about burn rates is that there is no industry-standard method for determining them.


It's not that one chart is "right" and the other one is "wrong"; they are both "right" (insofar as that word has any meaning here), but because the two different manufacturers tested these powders using different methods, they got different results.

One thing I will add is with a powder that is slow you will be using more to get the same velocity as a faster powder. And a lot of times the slower powder will be a compressed charged.

A good reloading manual like Lee's "Modern Reloading" will cover this subject and it makes for some very interesting reading. I would still urge caution when using over-length barrels though, I found that out.

One thing I will add is with a powder that is slow you will be using more to get the same velocity as a faster powder

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Well, probably, or at least possibly so. But I'm not sure that's important to know.

Yes, you probably will get to a certain velocity with a slightly lower charge weight of a faster powder. But you won't be able to (safely) use that faster powder to push that bullet to the velocities the slower powder could take you.

As an example, looking at that Nosler page I linked earlier, if you for some reason choose to load a 110 gr. .308 that only goes 3,230 fps, you can do that with 43 gr. of Reloader7 powder. To go that same speed using Benchmark powder you'll need to use something like 46.5 grains. So if going 3,230 is EXACTLY what you want, using RL7 saves you 3.5 grains of powder. (Around a penny to a penny and a half per round.)

However, using RL7, that's your max load. 3,230 is all you can get.
Using Benchmark you can keep going all the way up to a safe load of 49 gr. and that will move your bullet at around 3,364 fps. So, is your penny per shot worth another 134 fps? Probably.

And a lot of times the slower powder will be a compressed charged.

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Eh...well, sort of. Probably NOT a compressed charge if you're comparing it to the equivalent velocity with that faster powder. Using the example given above, at 3,230 fps, using Benchmark there will still be room in the case for another 2.5 gr. of powder.

There are lots of powders that do get into compressed loads at the top of their safe charge weights. The manuals will usually tell you that clearly so you don't get freaked out about it.
There are some powders that don't work well if compressed, but many do and there's no reason to worry about that. If the manual says compressed load, go right ahead and do it.

hdwhit said:

Keep in mind when thinking about burn rates is that there is no industry-standard method for determining them.

If you consult the burn rate chart published by Vihta Vuori, the "fastest" powder shown in Hodgdon Titewad followed by Alliant E3.

But, if you consult the Hodgdon chart, Titewad doesn't show up until number 6 and is "slower" than Alliant's E3 at number 5, both of which are "slower" than Norma R1, the powder Hodgdon says is "fastest".​

It's not that one chart is "right" and the other one is "wrong"; they are both "right" (insofar as that word has any meaning here), but because the two different manufacturers tested these powders using different methods, they got different results.

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What are the different methods? I imagine guys with horn rimmed glasses, clip boards, and white lab coats measuring how fast a trail of powder burns. I'm sure I'm way off, but it sounds cool, lol.

And what about lot to lot variation? Does that account for any of the differences we see on different burn rate charts?

Ultimately, your specific experience is the best data about what works best. As was repeated many times in this thread, loading manuals will point you in the right direction about which powders were tested and safely worked in a laboratory setting. Do this long enough, try various combinations, and you'll find what works for you and what doesn't.

Sometimes things are posted on the internet by keyboard experts that have little or no basis in fact. An example is a thread on this board some time ago where a poster responded to me when I named a powder that I liked for 30-06 loads by saying "there are 20 better powders" for that application. Well, I guess everyone's entitled to their opinion, right or wrong.

Experience is your best friend, followed by published manuals.

1) The powder that produces the highest velocity at safe average max pressure will always produce the highest velocity, whether the barrel is 2" or 32" long.
2) The powder that produces the smallest groups could be any where among the most viable powders, no matter what the velocities say.
3) Slow/fast "rating" changes depending on case volume, bullet weight, max average pressure, temperature of burning, and who knows what else
4) Never accept any comment about accuracy unless AVERAGE group size and distance is referenced. Accuracy must be reproducible to be meaningful, and not just some random great group that can never be repeated.
5) If a powder suddenly disappears and returns as bullet weight changes, you can pretty much assume that powder in that cartridge with that bullet weight where it is was not mentioned almost certainly threw up some very nasty pressure spikes and may not be that good for any weight bullet in that cartridge.

Walkalong said:

Too slow and you can't get enough in the case to reach good velocity.
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...or pressure, I found that out! IMHO bullets need to deform a bit (or a lot, in my case) to run well. Thank goodness for the load data.

"A good reloading manual like Lee's "Modern Reloading" " An oxymoron?

Specific info would help. If we knew which cartridge you are loading for and which bullet you are trying to use then specific answers could be given.

Most load manuals have a burn rate chart where all powders are listed in order. Usually from fastest to slowest. I'll use 30-06 as an example. With bullet weights from 150-180 gr IMR4350 or H4350 is a good choice. Or anything close to 4350 on the burn rate chart. Not saying 4350 is best, just that you'll get good results with powders close to it on the burn rate chart. With bullets 150 gr or lighter then powders faster than 4350 might be a better option. With bullets heavier than 180 gr you'll probably get better results with a slower powder.

You can still safely shoot lighter and heavier bullets and use the same powder. But a powder slower than 4350 will result in more speed and probably accuracy with the heavier bullets than you can get with either 4350. A faster powder would do the same with bullets lighter than 150's.

Lots of things come into play here.Powder burn rates can be helpful in narrowing down your choice of powders to try.Caliber,barrel length,primer type and bullet weight can influence what powder will work for a given load.One example-I have a Remington Model 7 in .243 Winchester.It has an 18" barrel.The 243 usually will like powders in the slower range,IMR 4350,Reloader 19 and such.In this short barrel rifle,these "slower" powders have a lot of muzzle flash and not the best velocity.I found that Varget works well,makes slightly better velocity and has a lot less flash.I would have to say that in that situation,powder burn rate was something that made a positive difference.The relationship of the bullet diameter to the case capacity is a major factor in what burn rate,therefore which powder will work best as a general rule.The more case capacity,the slower the powder needs to be.A 308 will need a faster powder than a 300 Win.The new Nosler rounds,the 26 and 28 Nosler will need very slow powders because of so much overbore,a term for rounds that put a huge case behind a relatively small bore.A round such as the 35 Whelen will use a relatively fast powder because of very little overbore.All that said,it is still prudent and wise to stay within the published data for the round you're loading for.However,burn rate can be helpful in customizing the ammunition to suit the rifle and it's intended purpose.Don't ever go by burn rate and try to plug in a powder that's not listed for what you're loading for.That is playing with fire,literally.

In 1996 IMR listed all their powders for a cartridge. Powders are listed from fastest to slowest.

The fastest 4759produce high pressure sooner with lower velocity.

The to slow powder 4831 produce lows of both pressure and velocity. They also fill the case sooner.
Powder- Grs - fps -pressure



C=Compresses powder charges.