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Powder Burn Rate

BEN243

I have seen two similar "Powder Burn Rate" temperature charts on the Internet. About the only difference I can see in them was the heat value listed for IMR4350. One lists the heat for IMR4350 at 3760, while the other chart lists it at 3900. Can anyone possibly tell me which one is correct ? Ben
 
Burn rate charts are about as accurate as the bible.
I do not take their information as meaning anything.
No powder company lists their burn rates to a set standard, so your guess is as good as anyone’s as to how each powder lines up...and, burn rates are not constant or set in stone.

Cheers.
 
At best, I use it as a guide to see which ones are at extreme ends and get an
idea which ones to possibly stay with or away from.
Or at least know what possibly to expect.
I usually go with what works best.
 
Here is one that is way off.

We were at the range today shooting out 7mm Geramo. H1000 has proven to be the go to powder for this case and the 162 Hornady ELD.

We are looking for an alternative, and N170, by all of the charts, looked like it might work. All of the charts list it as just a tad faster than H1000.

My load of H1000 goes out at 2840 or so with 56.2 grns. So, since the chart said N170 was just a little faster, I figured to start at 55 grns.

The Chronograph showed 2500 FPS, and the impact was 3 inches low at 200 yards. What the heck?

So I started increasing the load in .5 increments. At 58 grns, which is a full compressed load, the chronograph still only showed 2650 FPS. The rifle was shooting big .800 globs at 200 yards.

The chart is flat out wrong. N170 is at least 4 grns slower than H1000, not faster.

https://loaddata.com/Article/BurnRateCharts/Powder-Burn-Rate-Chart-NEW/159
 
Last edited:
What does "Heat" = 3900 or 3760 mean? The quoted numbers look like they came from a Quickload chart that has been posted in these forums many times, without any reference to what the numbers mean. Are there any units associated with this that could give any of us a clue as to what the heck they measured (if anything) to come up with a value of 3900? My guess is that it is just another relative number that is coded for use by the Quickload software and meaningless for any other use.
 
Burn rate charts should be broken down to a powder lots. they vary so much it would be a total joke. Burn rate varies so much with in a lot it can move you all over the chart. My 5 or 6 lots of H 4350 are a good example as is H 4895..... jim
 
It's heat potential of powder in Kj/Kg. A QuickLoad parameter.
This has no correlation with burn rate, and N133(faster) and H1000(slower) are both cooler(3630) than H4350.
 
Guys, I was just trying to get a comparison of how hot IMR4350 burns compared to some of the other powders I use. I thought maybe the charts I saw online might help with that, but have no idea where or how they came up numbers on the charts. Ben
 
BEN243 said:
Guys, I was just trying to get a comparison of how hot IMR4350 burns compared to some of the other powders I use. I thought maybe the charts I saw online might help with that, but have no idea where or how they came up numbers on the charts. Ben
Click to expand...
All burn rate charts and burn temp charts will do is get you confused or, worse, in dangerous situations.
There are a few powders that sit in the same relative place as H4350 on the burn rate chart. IMR4451, RL16 and RL17 are right there with H4350 but while each may be used in place of H4350 they are none the same. Case volume (density) of RL16 is perfect for stuff like 6 and 6.5 Creedmoor (also very wide accuracy nodes) while it does not have the density to make it good in 6.5-47L. The lot of RL16 I have is providing lower pressures than H4350 but I've heard otherwise in other lots. Also, those three powders have (even though not supposed to be) very different temperature sensitivity.
If you're looking at those heat factors to try and "game" the barrel wear issue then you're already lost.
 
mikecr said:
It's heat potential of powder in Kj/Kg. A QuickLoad parameter.
This has no correlation with burn rate, and N133(faster) and H1000(slower) are both cooler(3630) than H4350.
Click to expand...


I just talked to Hodgdon's technical (powder) people this afternoon. All of the powder we buy is from some manufacturer, with a specific name or number, which is unique to to the particular manufacturer. The formula and performance characteristics of that powder are "Proprietary" information to that manufacturer. The testing that is done by Hodgdon is to load certain cartridges to certain specifications, fire them in test barrels.
If the performance of the loads meets the required performance window, the powder can be sold as that company's particular cannister grade powder i.e. H 4895. Only the manufacturer knows how big the window is. There seem to be no Government standards for a particular cannister powder i.e. H 4895. There are "Mil Specs" for certain powders but not all by far. Hodgdon releases none of this information to the public. So it would seem to follow that they do not release IMR or Winchester information either. I would also believe the other powder manufacturers do the same. So any numbers such as KJ/KG, would seem to have to be derived from post manufacturer testing. I doubt those numbers are publicly available either. So as stated by others, simple lot to lot variations could move a powder in the burn rate chart.

I have a jug of Data 85. The story was that it did not make the desired performance window, and could not be sold as a known cannister grade powder. IIRC it was produced by Ramshot. It is to be used as Ramshot Hunter. That is a ball 4350 more or less. The story is that powder lots that can not be sold as cannister grade are sold to ammunition manufactures to load ammunition. There they can adjust the powder charge to meet the required cartridge performance.

I had some Vectan AO and when I tried to find out anything more than the basic info, it was French Government classified.

Jeffrey
 
mikecr said:
The folks at QuickLoad must have tested their lots of powders, for their numbers.
Click to expand...
Probably a tough thing to test, but if they know the chemistry they can calulate the potential energy based on the defined energies for specific bonds in the reactants (the powder) and the products (what's left after the powder burns). Remember balancing molecular equations in chemistry class, reactants on one side and products on the other? The difference in bond energy between the two is equal to the heat given off in the reaction (combustion). You just need to know what you have to start and what is left after combustion.
 
I try to avoid stepping in these discussions, but can't we all just get along? Believer or non-believer, evolution or no evolution; none of this matters when discussing burn rates of powder. Just as much as I don't want to see people preaching about the glory of god on the forum, I also don't want to read people making fun of (any) religion. I didn't come here for the holy wars, I came here to learn about reloading and shooting. Religion and politics are a quick way to derail any useful discourse and ruins the experience for everyone involved. Luckily, I think this thread has already run its natural course.
 
Jeffrey Tooker said:
Hodgdon releases none of this information to the public. So it would seem to follow that they do not release IMR or Winchester information either. I would also believe the other powder manufacturers do the same. So any numbers such as KJ/KG, would seem to have to be derived from post manufacturer testing.
Click to expand...

mikecr said:
The folks at QuickLoad must have tested their lots of powders, for their numbers.
Click to expand...

The QuickLOAD program compiler gets his default values from powder manufacturers. Most companies won't provide these data to the public, but some provide it on their websites and elsewhere. For example, Nammo Vihtavuori Oy gives both bulk density and specific energy values on all its rifle powders on its website:

https://www.vihtavuori.com/powders/n100-powders/

https://www.vihtavuori.com/powders/n500-powders/

European manufacturers seem much more willing to provide this information than their US equivalents - Norma Precision (Bofors manufactured), Nitrochemie Wimmins a.g. (Reload Swiss and some Alliant grades), Vihtavuori all do so. Norma also shows the nitroglycerin content of each of its grades which is pretty unique. (All Norma powders are double-based.) The shooting journalists who research and write Wolfe Publishing's Propellant Profiles features in Handloader magazine usually obtain these types of data from the manufacturers or US importers.

FWIW, QL's predictions in my use of both IMR and H4350 have proven pretty close to actual, in one recent case spot on for the Hodgdon version. Both are rated at 3,760 J/g in the program and they don't appear to be far out at that. Purely an opinion!

I somewhere have a feature in a very old handloading tome about this aspect (ie the manufacturers' use of 'closed bomb' testing to ascertain powder energy characteristics) which uses IMR rifle powders as its example. This was written back in Dupont Corporation days when IMR powders were manufactured in the US. One interesting point the article made was that all IMR rifle powders had the same energy value (which was given in BThU - British Thermal Units) such is the length of time since publication, and that the burning rate as opposed to energy levels was controlled through kernel size and the diameter of the central longitudinal hole as well as use of deterrent coatings. That may not apply now as IMR powders have been developed and manufactured for the Hodgdon Powder Co. by General Dynamics Valleyfield, in Valleyfield, Quebec Province, Canada for many years now.

I suspect that many energy values are an average or 'nominal' figure as actuals will vary perhaps considerably by production lot as noted in earlier posts. 'Canister powders' for handloaders are meant to be much more consistent than the bulk lots supplied to ammunition manufacturers. It used to be said that supplies from different lots were blended to achieve this, but I suspect that nowadays a lot that gives close enough results to the nominal values on testing will be diverted to the handloading supply side of the business. Vihtavuori has long prided itself on making exceptionally consistent powders, so it may not have to do this, or maybe not so often as its competitors.
 
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