Powder burning rates

C

cdoc42

New member
Powder burning rate charts are all "relative" rather than "absolute" and, as I understand it, may change slightly during lot production. But they are useful to review when choosing a powder to use. In 2004 I found a chart from a website which was just a list from fastest to slowest. I numbered them from 1 (fastest) to slowest (106) - example, IMR4895 is 70/106, and affixed those numbers to the powders I had in my inventory. In 2011 I found a chart from IMR which listed 144 powders, so I changed the numbers in my stock. IMR4895 was now 89/144.

The most recent list, I believe, I obtained from a Hodgdon site, and it contains 149 powders, so I updated my inventory once again. IMR 4895 is now 90/149.

The question may be, why go through all that? Well, when I open my powder cabinet I may see H414, H4831, W780, IMR7828 sitting there, and it's more meaningful to see the burn rate numbers, respectively, 112/149; 128/149; 130/149 and 135/149 to help assess the potential differences between them.

When a new powder arrives on the market, it's difficult to determine how it lines up with existing competitors. The burn rate helps. For example, IMR 4451 arrived and I had no quick idea where it might play a role. But its burn rate is 116/149 - which happens to sit right between IMR4350 (115) and H4350 (117).

Given these are so close, I'm left to wonder if it really matters much if that subtle difference in burn rate is significant. What's really the point of trying that "new" IMR4451?

One should also recognize the numbers listed are all sequential, and no two powders have the same burn rate. Even though H110 and W296 are exactly the same powders, H110 is 63/149 and W296 is 64. Why are they not both 63?

So I've found the real value in this exercise is when I want to get more rifle velocity by using a slower powder, I won't waste time choosing between two that are very close. I may be currently using H4831 (128/144), so I'll bypass W780 (130) in favor of either IMR 7828 (135) or H1000 (140.

Has anyone else wandered into this handloading arena?
 
"...may change slightly during lot production..." Burn rates are fairly consistent from lot to lot. Chemicals in the powders do it. However, the charts usually reflect more than one manufacturer's powders. And new powders are added or discontinued powders removed. That's what changes. Isn't really something you need to inventory or worry about.
 
You're way over thinking this. Yes it is true that powders burn rates vary over time. If you pick 2 powders very close on the chart and follow them over time one year one will be ranked faster, a few years later they'll swap places.

But in the grand scheme of things none of that really matters. Select the powders that work well for your application. Exactly where it falls in those charts isn't really all that important. Going slower or faster by several rankings is less important than how accurate they shoot in your rifle.
 
IMHO

The only true way to determine burning rates of any powder used,
is to look up the info on QL, (if available),
as QL uses the caloric closed bomb tests for testing powders in his software.

Anything else is just a SWAG.

I have read on numerous sites/posts that xyz powder is THE SAME AS zxy powder.
Not true in 99.5% of the powders quoted. :eek:

I have made a XL list of most all the US powders as listed in QL,
and if I remember right there is 6 powders that show the same,
Burn rate, Heat of explosion, and Rate of specific heat etc, out of a 140+ powders.

Since it's my face and eyes along with other body parts around the firearm,
I prefer to keep them attached as formed. :D

YMMV,

Tia,
Don
 
There are several Hodgdons / Winchester matches. There are also several Hodgdons / ADI matches.

Now add several Alliant / Norma matches and a couple of Accurate / Western / Vectan.
 
Powder burning rate charts are all "relative" rather than "absolute".
So I've found the real value in this exercise is when I want to get more rifle velocity by using a slower powder, I won't waste time choosing between two that are very close.
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I've yet to find burn rates as of much relative importance other than a curiosity. If I want to get more velocity, I go to my manuals and find a recipe that gives me more velocity. I still need a start load and a max load, a burn rate chart does not give me that. While just picking a slower powder may give me more velocity...sometimes in handgun calibers, that slower powder is too bulky and you can't get enough of it in a case to increase the velocity over a faster powder that takes up less case volume. Burn rate charts don't tell me that either....but my manuals do. The other thing burn rate has never given me, nor anyone else I know, is expected accuracy in a particular firearm. This is something many of my manuals give me, which powders worked best in their tests for accuracy within a particular caliber and bullet weight. Is there a reason most powder manufacturers/distributors make their burn rate charts just "relative", while their load recipes are quite specific? Maybe it has to do with whats really important. Again, burn rates are interesting....but they are only relative. Just as to me....velocity is only relative. Accuracy is what is absolute. I kill much more game and hit many more targets with accuracy than with velocity.
 
Burn rates can actually switch places depending on the capacity of the case in which you are using it. The main purpose of a burn rate chart is to find other powders that may work in place of the one you are using. However just because two powders have similar burn rates does not mean you can use the same data for both.

IMR 4451 is a newer powder in the 4350 range that is supposed to have additives to reduce copper fouling and reduce velocity variations over large temperature ranges. You must, however, use data designed for it. Identical powders will usually have successive listings on a burn rate chart. Because one power is listed just ahead of another does not mean there is any significant difference in their burn rates, or in other cases that they are the same. Different charts put some powders in different orders depending on who is doing the testing. The chart is just a starting place.
 
I think one of us is either over or under thinking the matter. I think your first sentence
Powder burning rate charts are all "relative" rather than "absolute"
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actually answers your questions.

Powder Burn rate lists are "relative". Relative to what???

Relative to EACH OTHER.

(lets put aside, for now, changing burn rates in different lots over time..)

Relative also meaning not directly fixed on a scale. The differences between the burn rates of the powders on the list is NOT a fixed value. It is not direct arithmetic progression, or even logarithmic progression. It is a variable, and can be small or large.

lets make a short list for illustration.

Bullseye, Unique, 2400

They are ranked here by their burn rate, relative to each other. All this tells you is that 2400 is slower than Unique, which is slower than Bullseye. That's ALL it tells you.

It does NOT tell you that the difference between the burn rate of Bullseye and Unique is much less than the difference between Unique and 2400. The same hold true through the rifle powders as well. The difference in burn rate between 89/160 and 90/160 in your system might be very small, while the difference between 90/160 and 91/160 could be several times the difference between 89 and 90. The burn rate lists DO NOT TELL YOU ANYTHING ABOUT THAT.

Also, burn rate lists don't tell you anything about a specific powder's applicability or suitability for a specific application. For some things some powders are too fast to reach peak performance. In other situations some powders are too slow for adequate performance.

So, when looking for more velocity, assuming the slowest powder will get you there, and skipping several (for example, going from 90/160 straight to 110/160) might not get you what you want, might even be dangerous.

Other factors than position on a burn rate list MUST BE GIVEN PRIORITY CONSIDERATION!!!!

And that consideration has to take into account all the specifics in your exact situation. All the ammo components and firearm characteristics.

burn rates are interesting....but they are only relative. Just as to me....velocity is only relative. Accuracy is what is absolute. I kill much more game and hit many more targets with accuracy than with velocity.
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I'm pretty sure I understand what you mean by this, but I must, (pedantically) point out that without velocity, you won't hit or kill anything. :rolleyes:

Both are needed. :D

I do agree that velocity without accuracy is of very little practical use.
 
Burn rates are only half the equation. The number that is not available, or at the least hard to find, is burn energy. Amount of energy released per gn of powder is equally as important as the rate at which that energy is released.
 
Burn rates are only half the equation. The number that is not available, or at the least hard to find, is burn energy. Amount of energy released per gn of powder is equally as important as the rate at which that energy is released.
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I'll grant that they are parts of the equation, but I don't think is half.
Of course, I'm not certain just which equation you are talking about...:confused:

Something I haven't seen mentioned yet, is the fact that modern powders are progressive. They burn differently under pressure than in open air. And that pressure will vary with different cartridges and loads. How many calories/gram (or whatever units one uses to measure) will be one number in open air, and likely a different number under different pressures.

Again, its relative.

;)
 
Propellant burn rates are about as clear as mud. Variables abound.

I've looked at a lot of charts. And one over-arching concern I've had is with the "perceived linearity" of charts that simply number the powders from 1 to Whatever. I think they lend themselves to painting an inaccurate picture.

Hodgdon's burn rate chart is a popular example. And in the case of Hodgdon specifically, they position some powders that just leave me shaking my head.

For example, they have AA#5 at position 41, slower than Power Pistol (pos 34). It's been my experience that AA5 is pretty fast for an intermediate speed powder - very close to Unique (pos 31). I find Power Pistol to be about the same burn rate as HS-6 (pos 42), albiet, more energetic (per reynolds357 & 44 AMP's post).

Hodgdon has HP38/W231 (pos 28, 29) slower than AA#2 (pos 26) - it's not. AA#2 is actually pretty slow for a fast burner. And I find TiteGroup (pos 15) to be virtually the same speed as AA#2; and Hodgdon has TG sitting very close to the very speedy Bullseye (pos 13). That's a serious head-shaker for me.

I like the Accurate Arms/Ramshot chart. First, because it is non-linear, so it doesn't imply something that isn't true. It has rows that show powders at (or very near) the same burn rate; and this makes much more sense to me. Secondly, it has the propellant's burn rates correctly positioned based on my personal experience. It shows Bullseye a tick faster than HP-38/W231; and HP-38/W231 a tick faster than AA#2, TiteGroup, & Red Dot; and AA#5 a tick faster than Unique; and Unique a tick faster than Power Pistol and HS-6. These all fit in perfectly with my personal experience.

All said, I think it's important to contemplate burn rates in the context of the full picture of loading. All told, even if the perfect burn rate chart existed, it's only a guideline to point you in the right basic direction to fulfill a loading purpose. It is just a basic step early in the process of creating ammunition specific and correct for a purpose. Context and perspective.
 
I get where he is coming from.

And again, understood its relative, but say you are looking at things and you know 4350 is a good go to 30-06 powder, 4831 is as well.

So then its, well, I want to get more velocity, XXX is faster than 4350. Don't know how much but its quicker.

Ok, pull out the loading books (always TWO) and well I will be darned, XX is there, move that puppy along another 200 fps over 4350. Bingo and I have it as well.

Granted, you can just open up Sierra or Hornady books.

They are also behind newer powders.

So you go to the power mfg, get their data, cross compare, fine out and get some idea of where it falls into the scheme of things.

It would be better if there was an actually a relativistic number that had relevance but again I get it, feel he same way.
 
Can someone weight in (pun intended) if those new powders are better than the older ones in any reality?

I too am wondering.

During our powder shortage, they came out with a lot of new fangled powders, I would have been happy if they just provided the ones they had previously!

Are they getting us something or is it just new whiz bang, zap 9 and Z7 and its the same old thing?
 
So you go to the power mfg, get their data, cross compare, fine out and get some idea of where it falls into the scheme of things.
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One itsy bitsy little problem. Hodgdons doesn't manufacture smokeless powder; they distribute; many of their powders come from ADI, some from St. Marks. Accurate and Western... distribute Vectan and St. Marks. Alliant and Norma get their rifle powders from Bofors...again distribute.
 
Do any of you own or run the Quick Load program?
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I'm a dinosaur, I neither own nor run any computer ballistic/reloading programs. I can barely manage chat on the forum,.;)

I would also like to remind everyone that no matter what any computer program or test lab gets for results may NOT be what you get from your firearm and components, even if you are as close to exactly the same as you can get to their test components.

You might find that a powder that shows it gets 200fps more in the books (or on the screen) MIGHT not do that in the real world in your gun.

Similar results are to be expected, but different results are common and very different results are not unheard of.
 
Do any of you own or run the Quick Load program?
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I'm old-school too. But I do have QL.

Keep in mind, I only load for handgun . . .

It's a nice program to have, but I don't find it particularly useful. It seriously lacks bullet choices. I often run into times when the bullet choices bear little resemblance to what I'm using - lacking even a reasonable substitute. But even with that, it manages to come in handy on occasion.
 
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