Table of powder consistancy.
- Thread starter AJC
- Start date
bozo699
Gold $$ Contributor
I can’t answer your exact question but I’ve shot a lot of varget. I’ll get burned for this but it does vary, I try to buy quantity of same lot number but if I have a couple of one lot number and a couple of another I mix it all together then I have my own lot number. I load with chronograph and if I need to add or subtract a tenth or do to keep my 6brx at my selected velocity that’s what I do.
Wayne
I've even heard wild stories about people buying 8 lb of singles and mixing it in an 8-pounder so they don't have to reformulate a bunch of times
Military tested 6* different lots of H4831. Very wide spread in velocity & pressure from the slowest to fastest.
Possible dangerous pressures.
I would never blend or mix lots of any powder.
https://apps.dtic.mil/docs/citations/ADA572333
"To consider the likely pressure variations, consider that QuickLoad V3.6 predicts a muzzle
velocity of 3174 ft/s and a peak pressure of 54371 psi for 79 grains of H4831 using the 155
grain AMAX in the .300 Win Mag. This is very close to the 3177.5 ft/s velocity that results from
averaging the measurements over all six lots of powder. However, compensating for possible
lot to lot velocity variations requires a range of powder charges spanning from 77.5 to 80.5
grains of powder and a range of pressures from 51063 psi to 57910 psi. It is possible that a
load showing no signs of pressure with one lot of powder might not be safe with another lot of
powder. At their web site, Hodgdon recommends working up new loads when the lot number
of any component is changed, and it is evident that this includes a new lot of Hodgdon."
Possible dangerous pressures.
I would never blend or mix lots of any powder.
https://apps.dtic.mil/docs/citations/ADA572333
"To consider the likely pressure variations, consider that QuickLoad V3.6 predicts a muzzle
velocity of 3174 ft/s and a peak pressure of 54371 psi for 79 grains of H4831 using the 155
grain AMAX in the .300 Win Mag. This is very close to the 3177.5 ft/s velocity that results from
averaging the measurements over all six lots of powder. However, compensating for possible
lot to lot velocity variations requires a range of powder charges spanning from 77.5 to 80.5
grains of powder and a range of pressures from 51063 psi to 57910 psi. It is possible that a
load showing no signs of pressure with one lot of powder might not be safe with another lot of
powder. At their web site, Hodgdon recommends working up new loads when the lot number
of any component is changed, and it is evident that this includes a new lot of Hodgdon."
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I'm not trying to condone or dissuade anybody from doing anything I'm just trying to get information. People that shoot competition are already exceeding book Max in some cases and I could see the danger and shifting lots and not backing off.
Ned Ludd
Silver $$ Contributor
Any time I get a new Lot of powder, I usually determine an average velocity from a 2% reduced load using exactly the same Lot# of the other components (brass, primers, bullets). I then plug the average velocity into QuickLoad, and it gives me a pretty good idea of how much the burn rate for that particular Lot varied from the last. I've had Lots of Varget and H4895 that might have varied by as much as 50 fps from the previous Lot for a given charge weight, perhaps even a little more. However, I don't typically load at, or way over, SAAMI MAX to begin with, and an increase of ~50 fps won't typically be enough when using Lapua Palma brass to even give hard bolt lifts. If you're running a load that is already pretty hot, it could be problematic. For safety, that is why I test with a 2% reduced load to start a new Lot.
I had a bunch of Varget and H4895 one pounders from different Lot#s left over from an earlier powder dry spell, and I ultimately made a Varget "mix" and a [separate] H4895 "mix" a couple years ago. Before mixing the Lots together, I did the 2% reduced velocity test with each different Lot#. The ES for those particular Lots was only about 15 to 20 fps total, and the final velocity of each mix was very close to the weighted average of each individual Lot. I ended up with two individual mixes of Varget and H4895 of about 16 to 18 lb total per mix, and have been using them in both .223 Rem and .308 Win F-TR loads for some time. They have worked extremely well, I cannot state with any certainty that the mixes have behaved any differently than any other individual Lot# of either powder I have used. Once the load has been properly tuned in, the ES/SD values I have obtained with either mix have ben indistinguishable from a single [pure] Lot# of powder. I have also seen a few people report here and elsewhere that they routinely pour the remainder of a nearly empty jug of powder into a freshly opened jug from a new Lot#, mixed it up, and used it as normal.
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Sorry if my statement sounded harsh. Just saying its not to my liking. Just my 2 cents.
I started comparing the weight of a new lot to old lot. The new lot is heavier then the old powder. This was with 3 different powders.
Drop the powder out of the measure with the same volume setting. Always run 20 drops to settle the powder first. Then weigh 10 volume drops for an average.
Compare both.
dgeesaman
Gold $$ Contributor
Honestly, this request is basically asking for quality control data.
The manufacturers may have it, but they sure as heck wouldn't share it. If an independent source tries to measure it themselves, I suspect they'd be told to take it down.
I think we're stuck with the basic paradigm of "work up a new load for each lot #". It should be a matter of tweaking powder charge.
The manufacturers may have it, but they sure as heck wouldn't share it. If an independent source tries to measure it themselves, I suspect they'd be told to take it down.
I think we're stuck with the basic paradigm of "work up a new load for each lot #". It should be a matter of tweaking powder charge.
The burn rate of a powder will change with temperature and pressure, that is to say on a hot day velocities will be higher and a load running at say, 55kpsi will have a different burn rate than one running at 65kpsi.
Loading ammo with QuickLoad and a LabRadar it easy to see the influences of both temperature and pressure, velocity is the marker.
If I have a perfect load ( on a node and low ES) it will run a certain velocity, say 2820 ft/s. When powder lots are changed I load up 5 rounds and check for velocity. If the velocity is now 2855 ft/s , I know the powder lot is a bit faster than the previous lot, with no other changes.
In the Quick Load program I will change the burn rate (Ba) to reflect the new velocity. Now my barrel time will be off (OBT), so the charge weight is lowered to match the original barrel time. Works the same way if burn rate of new powder is lower.
Most of my loads run in the 55kpsi to ~62kpsi. If I need the velocity to catch a higher node then the pressures can be as high as 67kpsi, I go no further in this case .
A powder and component change sometimes will get on a higher velocity node within industry standards for pressure, without exceeding it.
Loading ammo with QuickLoad and a LabRadar it easy to see the influences of both temperature and pressure, velocity is the marker.
If I have a perfect load ( on a node and low ES) it will run a certain velocity, say 2820 ft/s. When powder lots are changed I load up 5 rounds and check for velocity. If the velocity is now 2855 ft/s , I know the powder lot is a bit faster than the previous lot, with no other changes.
In the Quick Load program I will change the burn rate (Ba) to reflect the new velocity. Now my barrel time will be off (OBT), so the charge weight is lowered to match the original barrel time. Works the same way if burn rate of new powder is lower.
Most of my loads run in the 55kpsi to ~62kpsi. If I need the velocity to catch a higher node then the pressures can be as high as 67kpsi, I go no further in this case .
A powder and component change sometimes will get on a higher velocity node within industry standards for pressure, without exceeding it.
Murray Brook
Silver $$ Contributor
As far as mixing powder lots what I do is take the velocities of several rounds of the different lots. If the velocity is close then I mix, if not I don't.
Indeed this is exactly what I was looking for and this would be the level of shooters that went through enough volume and kept enough records to provide some quality useful insight
CharlieNC
Gold $$ Contributor
Absolutely!
Ned Ludd
Silver $$ Contributor
I suspect that even the manufacturers don't have a single burn rate value that would be useful to most shooters. Powder burn rates are dependent on many factors, pressure and temperature being two very critical ones. The exact same Lot# of powder is likely to have different burn rates in two different cartridges, especially if they are of markedly different size and/or are loaded with different weight or diameter bullets. There are too many variables involved to have a manufacturer-generated "one-size-fits-all" kind of value, so we test when we get a new Lot# of powder, and we generally try to buy as much quantity of a new Lot# as we can so that it lasts a while. It can be a minor PITA at times, but it's not really all that bad in the grand scheme of reloading.
I'm talking about a scientific test that standardized the compare one lot to another I don't care if they use a 1cc square a 1M Square they have a the ability to run a standardized test to know from lot to lot if the speed is increased or decreased
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Search here also https://discover.dtic.mil/
Buy one of these. https://oehler-research.com/system-85-ballistic-instrumentation/
Buy one of these. https://oehler-research.com/system-85-ballistic-instrumentation/
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You plan on getting one
The company has the information they just dont give it. People who shoot the same powder see the change and know. This would be a community effort and I dont have the ability for coordinate something like that.
Ned Ludd
Silver $$ Contributor
I'm sure the manufacturers have specs or a burn rate "window" that a given Lot must fall into to pass QC. Nonetheless, what I'm telling you is that the variance in powder burns rates is not linear. In addition to Lot-to-Lot variance, Burn rates are also dependent on differences in pressure and temperature, meaning the difference between the burn rate of two Lot#s may not be exactly the same in two different cartridges, or when using different weight bullets. You can accept that or not, but the fact is that there are too many variables involved. No powder company is ever going to provide you with some number stating - This specific Lot# has an exact burn rate of "X", that can then be directly compared to some other Lot# in a useful way. It isn't going to happen. I have no doubt they have detailed burn rate data for every Lot of powder they produce. Nonetheless, the burn rates they have determined are valid, and therefore directly comparable, only under the exact conditions under which they were determined. Even if they did provide users with such a number, it wouldn't be spot on for every cartridge and bullet weight the user might select. It might get you close in some circumstances, and still be off by a significant margin in others. So then you're right back to the same place, which is Lot-to-Lot variance in powder burn rate/pressure/velocity. That is why a simple charge weight/velocity test is necessary to figure it out.
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