BHP9
Well-Known Member
This^^^^^
I have found that the burn rate is different is difference cartridge cases. ie. The same powder used in .223 and .308 or 30/06. This was reported in a gun rag at least 30 years ago.
Accurate Burn Rate chart that compares Hodgden-Alliant-Viht powders
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This^^^^^
I have found that the burn rate is different is difference cartridge cases. ie. The same powder used in .223 and .308 or 30/06. This was reported in a gun rag at least 30 years ago.
The Vihtavouri website has a pretty good chart with the various manufacturerslisted side by side .
Yes, this is a known......thats why all burn rates are RELATIVE.
If you take all these powders and shoot them in .223 vs. .308 yes you will get different absolute burn rates for them in .223 cases vs. .308.
But their relative measured burn rates should still corelate in the order of the stack in
.223 or in .338.
Burn rate varies with both temperature and pressure and pressure is a function of volume.
So, ABSOLUTE numerical values will vary if you change the volume and pressure and temperature.
But RELATIVE relationships should still stack up about the same from powder to powder.
There is "somewhat" consistent method used across the industry to measure burn rate in the lab using a pressure bomb with contolled temperature and volume.
I will give link to the Army's process who started this research.
Here's a research paper on the Army's method when they first started looking at burn rate classification.
MagnumManiac
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Again, you believe something that is false.
It is not RELATIVE because no 2 powders from different companies has EVER been tested side by side. They all do their own calorimeter bomb tests and publish THEIR findings. What they do not publish along with that list is which powder they baseless this off. The interesting thing about a calorimeter bomb test is the fact that it isn't a cartridge simulation, it only records heat, pressure and time WITHIN a closed pressure vessel that allows expansion but no exit occurs. It is this RQ number that the burn rate chart is based off.
This is why a RELATIVE burn rate chart is often not even close and, more often is actually wrong with it's listed relationship groupings.
For example, in certain bore sizes and cartridge sizes, let's call it Expansion Ratio, many powders switch their burn rates on the list. In the 338WM, RE19 gives the higher velocities with 210g-225g bullets over slower powders because the volume is perfectly matched to the pressure reached, while RE22 lags behind until you get to 250g bullets and heavier. Same happens in certain cartridges with Varget and H4350.
Cheers.
I spent 4 minutes looking at this paper, you'd have to be a physics PHD to understand that ha ha. I just load em until I get as good as it will get with my limited knowledge, worked so far!
Son of a Gun!
Well-Known Member
Think I'd go with the first chart as most reputable as it comes from major powder distributor Hodgdon
Peter Morton
Well-Known Member
I know they're not perfect, but I've got to start somewhere when I'm selecting a powder. The last thing I need, and others may do their own thang, is a 50-page burn rate chart while I'm looking at the one powder in stock at the LGS and wondering if it will do the job.
Dont you know Its all RELATIVE?
Its as relative as it can be with as I said a "somewhat" consistent pressure bomb testing method that is not exactly the same from powder co. to powder co. Its not exact. I agree with you that powders from one chart to the next switch places sometimes and that can be very misleading and frustrating......I agree with you that
changes in cartridge size (volume)
and bullet weight( a proxy for pressure) and even the temperature in the pressure bomb or the cartridge/ chamber will cause changes to the burn rate.
Charts are for rough granularity of sorting only. US 869 is always gonna be slower than H4895 under any practical set of temperature, and pressure and volume conditions.
I suppose in the PVT equations you might find some very extreme boundary condition where its not so, but it would be an artificially created circumstance, not encountered in the real world usual range of expected boundary conditions.
On a rough relative stack, 4895 is always faster than US 869.
So, I dont like using the charts as much as I like using the values from QL. The designers of QL as explained by Chris Long in his white paper have tried to look at all the burn rate information supplied by manufacturers and users and true it in the software to get more accurate predictions.
QL also adjusts the starting burn rate input for specific pressure, and temperature inputs to model the actual conditions. It also accounts for the volume of every cartridge used measured by water weight, and it of course accounts for bullet weight and barrel friction, even seating depth.
But you have to start some place.
The initial model inputs are not perfect. QL did not get samples of all the powders and run a lab bomb test on all of them side by side under identical conditions.
But their numbers are as close as you can get. Not exact, not perfect, but darn close. A relative ranking of their model inputs for burn rates is the best "relative ranking" that I know of. Perhaps the DOD or someone else has some data that is non public, but no one has access.
If I have mis stated anything, it was not that I mis stated that the powders are RELATIVE to one another in their burn rates. They are.
Where I may have mis stated is in even considering that there is ever an ABSOLUTE value for any burn rate.
PVT conditions can occur in any mix and any combination meaning the absolute value of the burn rate can be almost anything depending on a range of values and permutations of pressure, volume, and temperature.
But, if we try to stay within some normally expected range of boundary conditions, there is a more narrow range or standard deviation of "psuedo absolute"
values for burn rate we can talk about. And then if we rank these on a relative basis, we have our RELATIVE stack.
So thats what I believe about relativity.....Its all relative.
Its as relative as it can be with as I said a "somewhat" consistent pressure bomb testing method that is not exactly the same from powder co. to powder co. Its not exact. I agree with you that powders from one chart to the next switch places sometimes and that can be very misleading and frustrating......I agree with you that
changes in cartridge size (volume)
and bullet weight( a proxy for pressure) and even the temperature in the pressure bomb or the cartridge/ chamber will cause changes to the burn rate.
Charts are for rough granularity of sorting only. US 869 is always gonna be slower than H4895 under any practical set of temperature, and pressure and volume conditions.
I suppose in the PVT equations you might find some very extreme boundary condition where its not so, but it would be an artificially created circumstance, not encountered in the real world usual range of expected boundary conditions.
On a rough relative stack, 4895 is always faster than US 869.
So, I dont like using the charts as much as I like using the values from QL. The designers of QL as explained by Chris Long in his white paper have tried to look at all the burn rate information supplied by manufacturers and users and true it in the software to get more accurate predictions.
QL also adjusts the starting burn rate input for specific pressure, and temperature inputs to model the actual conditions. It also accounts for the volume of every cartridge used measured by water weight, and it of course accounts for bullet weight and barrel friction, even seating depth.
But you have to start some place.
The initial model inputs are not perfect. QL did not get samples of all the powders and run a lab bomb test on all of them side by side under identical conditions.
But their numbers are as close as you can get. Not exact, not perfect, but darn close. A relative ranking of their model inputs for burn rates is the best "relative ranking" that I know of. Perhaps the DOD or someone else has some data that is non public, but no one has access.
If I have mis stated anything, it was not that I mis stated that the powders are RELATIVE to one another in their burn rates. They are.
Where I may have mis stated is in even considering that there is ever an ABSOLUTE value for any burn rate.
PVT conditions can occur in any mix and any combination meaning the absolute value of the burn rate can be almost anything depending on a range of values and permutations of pressure, volume, and temperature.
But, if we try to stay within some normally expected range of boundary conditions, there is a more narrow range or standard deviation of "psuedo absolute"
values for burn rate we can talk about. And then if we rank these on a relative basis, we have our RELATIVE stack.
So thats what I believe about relativity.....Its all relative.
MagnumManiac
Well-Known Member
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- Messages
- 5,557
@Veteran,
What you are saying is as broad as the burn rate chart is.
The OP is trying to use a burn rate chart to find a powder(s) that are clumped together to choose one to use.
What I am saying is that even though those powders are clumped together in a group of so called similar burn rates, this is most likely not so DEPENDING ON CARTRIDGE SELECTION.
Just because one powder company says that xxxx is RQ100, that doesn't infer that xxxx is the same from another company.
We all know through testing that IMR4350 IS faster than H4350…..the burn rate chart does not say this. This is my point.
As I previously stated, forget the burn rate charts when selecting powders. Look at books, lots of them, and compare what top 3-5 powders are always at the top of the list and give high load density and the highest velocity.
My mate uses Varget in his 30-06 for one simple reason…..it doesn't require a case full of powder, he's cheap and the performance is right for him, it goes bang and hits what he aims it at.
This above is not efficient, but it works.
Cheers.
What you are saying is as broad as the burn rate chart is.
The OP is trying to use a burn rate chart to find a powder(s) that are clumped together to choose one to use.
What I am saying is that even though those powders are clumped together in a group of so called similar burn rates, this is most likely not so DEPENDING ON CARTRIDGE SELECTION.
Just because one powder company says that xxxx is RQ100, that doesn't infer that xxxx is the same from another company.
We all know through testing that IMR4350 IS faster than H4350…..the burn rate chart does not say this. This is my point.
As I previously stated, forget the burn rate charts when selecting powders. Look at books, lots of them, and compare what top 3-5 powders are always at the top of the list and give high load density and the highest velocity.
My mate uses Varget in his 30-06 for one simple reason…..it doesn't require a case full of powder, he's cheap and the performance is right for him, it goes bang and hits what he aims it at.
This above is not efficient, but it works.
Cheers.
Rflshootr
Well-Known Member
This is exactly correct. Depending on case volume, column width and height and a variety of other things, powders can switch positions on a burn rate chart dramatically. That is why it is called a "Relative Burn Rate" chart.
Well tell the OP exactly what I said 2 pages ago. Get some powders, get some bullets , get a chronograph and go to. Proof is in the pudding.
Post the results here so we can which end is up
James DeTorre
Well-Known Member
While on substituting powders. My 280ai really thrives on 160 ABs pushed with H1000 of which I have none. What would be closest .?
WildRose
Well-Known Member
I switch back and forth depending on availability between RL26 and H1000 in my smaller magnums like the .300wm and I loaded a bunch of 7RM for a friend with very good results.
You can check Alliant's website to see if there's any 280ai Data or get someone to run those through QL for you with the bullet you prefer.
Reloder 26 in 280 Ackley
Messed around with some temp sensitivity testing today...I was testing Norma MRP...it failed miserably at 2.9 fps per degree...so I went straight to the fun store and got some Reloder 26. 61 grains of RL26 under a 160 Accubond....3,017 fps ES....34 SD....17 10 rounds That's the...
280 AI RL26 load work up, these two were made for each other.
Decided to try RL26 in the 280 AI I just back from Cooper with a new barrel. I loaded 35 rounds total for break in and load development RL26 CCI200 Nosler Brass Berger 168 seated .005 jam I cleaned the barrel before shooting any rounds Mounted the scope, looked through the bore and adjusted...
www.longrangeonly.com
The above are some guys working up loads with RL26.
