Unique hotter?

[willy]

Some types of powders are more susceptible than other types. It's just one of those "variables" that we mostly have little control over. What I do is store my powder in an old commercial refrigerator (no freezer compartment). My reloading is done in my small garage (man cave) with the temperature mostly held at a constant 75 degrees +/-.

The humidity doesn't fluctuate much down here in the desert country. When I lived up north in Washington and Oregon I had numerous top end loads for various cartridges. I began pressure testing when I still lived up there. Those loads pressure and velocity tested just fine. The powder was then stored in a wall locker in my garage up there with no temperature of humidity control. Of course those loads were loaded with the powder exposed to much higher humidity and lower temperatures.

After moving down here to western Arizona I tested those same loads loaded with the same powders out of the same jugs with nothing changed other than a year + in the desert temps and lower humidity. I found dramatic increases in velocity and, in some instance, pressures. Interestingly I found no velocity/pressure change in the hermetically sealed US 7.62, 5.56 and 45 ACP ammo. That's when I put my own powder supply into "climate control" as best i could. After about 6 months the variations due to humidity changes stopped.

Speaking of different effects on different powders humidity can have, I found in the 44 Magnum, the velocity/pressures of 2400 remained pretty consistent between loads up north and down here with the very same powder. However, when the same jug of H4227 was tested the velocity/pressure showed a marked increase. It's just one of those things.......

Makes sense…I guess my powder is just dried out a bit causing higher velocity with the lighter weight powder.
I may have to run some tests.
Put some powder in a high humidity area for a month,,And the same powder in a room with a dehumidifier running for a month ,,then check loads with each.

[Bmi48219]

While not an expert I tend to agree with Larry’s observation in post #15. I have a few powder measures preset for specific go-to charges. Therefore while the volume is constant and my loading procedure doesn’t change the weight of the charge dropped goes down slightly when I start using a new container of the same powder.

[Bmi48219]

Makes sense…I guess my powder is just dried out a bit causing higher velocity with the lighter weight powder.
I may have to run some tests.
Put some powder in a high humidity area for a month,,And the same powder in a room with a dehumidifier running for a month ,,then check loads with each.

You’ll want unbiased confirmation. Send a couple pounds of powder and a thousand primers to me in Florida for certification.

[44MAG#1]

I asked about the plastic containers that are in use today.
While I know that NOTHING IS PERFECT, if one keeps the lid on tight and keeps the powder in close to the same environment how much difference could humidity make. Or does the plastic containers hold no advantage to keeping out humidity?

[Larry Gibson]

A lot of testing has already been done. A lot of information in this read. Try; https://chronoplotter.com/2021/08/19...-affect-powder

If that doesn't work google "How does humidity affect powder performance?"

[44MAG#1]

Again I asked "I asked about the plastic containers that are in use today.
While I know that NOTHING IS PERFECT, if one keeps the lid on tight and keeps the powder in close to the same environment how much difference could humidity make. Or does the plastic containers hold no advantage to keeping out humidity"?
Asking if THE PLASTIC containers have an advantage?

[Larry Gibson]

"There’s no way to know for sure what happened with my 6.5 Creedmoor load, however I’d been loading from the same 8lb H4350 jug since the winter. It’s very likely my powder was dryer during load development, then re-hydrated as spring and summer progressed. A 21% change in RH would easily account for the 54 fps change in velocity."

That's the conclusion Litz came to after his extensive testing. It is in the article I gave you the reference to. Apparently the plastic jug is no guarantee. He recommends consistency in storage.

[44MAG#1]

It seems to me the more educated I get the less I pay attention to loading data no matter the source.
It seems like there are so many variables in what can make a load good or bad or safe and not safe that it is like playing the roulette table.
I just got loading the 173 Keith in 38 Special cases and am now scared to shoot them in my GP100.
I may go tomorrow and buy a welding Helmet stand behind a tree and wrap my arms around it and just point and shoot the best I can
Wish me luck.

[TD1886]

"There’s no way to know for sure what happened with my 6.5 Creedmoor load, however I’d been loading from the same 8lb H4350 jug since the winter. It’s very likely my powder was dryer during load development, then re-hydrated as spring and summer progressed. A 21% change in RH would easily account for the 54 fps change in velocity."

That's the conclusion Litz came to after his extensive testing. It is in the article I gave you the reference to. Apparently the plastic jug is no guarantee. He recommends consistency in storage.

.....and which way did that velocity change in relation to the humidity? Up or Down?

[44MAG#1]

The velocity went down in an area that had less humidity in Wyoming .
My head is spinning.

[TD1886]

The velocity went down in an area that had less humidity in Wyoming .
My head is spinning.

That is correct 44mag as believe it or not more humidity makes the air less dense. Look it up.

[44MAG#1]

That is correct 44mag as believe it or not more humidity makes the air less dense. Look it up.

So in my limited study the velocity should have increased in less dense air not dropped.
I am probably incorrect as I am in everything else

[TD1886]

So in my limited study the velocity should have increased in less dense air not dropped.
I am probably incorrect as I am in everything else

Yes it should increase in less dense air. Many confuse water as being more dense then air, but when it's in the air it's not in the same water form as say water in a pond. Moisture in the air displaces air molecules and spreads them out. So the more humidity the more the air molecules are displaced.

[44MAG#1]

Yes it should increase in less dense air. Many confuse water as being more dense then air, but when it's in the air it's not in the same water form as say water in a pond. Moisture in the air displaces air molecules and spreads them out. So the more humidity the more the air molecules are displaced.

So with Wyoming having less humidity the air is more dense so velocity dropped.
So as I said with all the variation loading data and loading is a roll of the dice.
Now we have humidity, air density, lot to lot variations of powder and primers and temperature, chamber and bore dimensions, seating depth, crimp and probably a laundry list more things that affect data, not to mention misprints of data, it becomes more of a roll of the dice.
So what is one to do?
So there is no way possible that a hot lot of Unique could ever in any way ever at all get out of the factory?

[44MAG#1]

I am sure since Laflin and Rand developed Unique in 1900 there has been no change to any of the ingredients/components in it at all and all the suppliers of all the ingredients/components have been the same and have been mixed and mingled together to make sure the burn rate has been the same since the first master lot of Unique was first formulated and tested in 1900 so it will be the same then, now and forever more.
I believe it.

[Larry Gibson]

..........So what is one to do?......

Ammunition manufacturers seldom load their ammunition to the full SAAMI MAP (Maximum Average Pressure). There are to other pressure figures used. It's sort of like a "safety factor" to account for all the probable variables. That's also the of the reasons most newer loading manuals have reduced their loads in many cartridges because, with modern pressure measurement, it accounts for many of the variables.

Also, Mr. Litz based on his testing, believes [it's in the article referenced above] humidity may also be altering the burn rate somewhat.

Not suggesting the same for anyone but here is what I have done to mitigate the adverse effect of humidity chance on powders. Here in the arid, low humidity SW desert in my reloading area where I sored my powder in a cupboard the afternoon temp inside could hit 100+ degrees when the Sun hit the garage doors. After understanding [observing the increase/decrease in measured psi of standard loads and researching the problem] the adverse effect a change in humidity I got a small commercial refrigerator [no freezer compartment] to store the powder in. I then also had a heat pump installed. That maintains the temperature at 75 +/- degrees and the humidity remains fairly constant between 10 and 25% year round.

That seems to have stabilized my powder. When I get a new/old cannister of powder I open it and put it in the 'fridge to "stabilize" humidity wise. A couple years ago I picked up an unopened can of Hercules Bullseye back in Florida. I got home to Arizona I opened it and let it "stabilize". Pressure testing it against Alliant Bullseye, also "stabilized" in the same 'fridge, in the 9mm and 38 SPL have shot, essentially, no difference. That is the same with Hercules Unique, Herco, Bluedot and 2400 when pressure tested against the newer Alliant same powders.

I don't think it is a "roll of the dice" if we follow reliable, modern, load data that has been actually pressure tested. I'm not saying to be anal about it, just saying to be mindful possible variables and keep safe.

[44MAG#1]

So, in summary, I am getting that there is no possible swings in "lots" of powder.
It is all in the way it is kept stored and handled.
All powder is so close in "Lots" there is no practical difference
Is this true in primers also?
No difference in primers, right?

[Larry Gibson]

So, in summary, I am getting that there is no possible swings in "lots" of powder.
It is all in the way it is kept stored and handled.
All powder is so close in "Lots" there is no practical difference
Is this true in primers also?
No difference in primers, right?

There is lot to lot variation in cannister powders we use. How much is allowable is a trade secret no doubt. I read years ago allowable lot to lot variation for IMR 4895 was 5%. Whether that was + or - wasn't known.

Probably some lot to lot variation in primers also.
I've not

[44MAG#1]

Here is a list I came up with on the variables on velocity variation that make it even more difficult to comprehend one results when chronographing.
If any one knows of more feel free to add them.

1. Lot to Lot variations in powder. MAYBE
2. Lot to Lot variations in primers. MAYBE
3. Humidity effects on powder.
4. Temperature effects.
5. Air density.
6. Inaccurate scales
7. Inaccurate reading of scales.
8. Different amounts of bullet
In case. Although same
Weight bullets
9. Amount of crimp.
10. Amount of neck tension
11. Different case columns
12. If low density loads where
The charge lays in case.
13. The need of a fresh battery
In Chrono.
14. Improper operation of
Chrono.
15. Different barrel length than the loading data used.

[WRideout]

As far as humidity getting into a closed plastic can, ambient temperature changes can cause a partially filled container to "breathe." Once the seal is broken, there is no guarantee that air will not be moving in and out of the container until equilibrium with the outside air is achieved. Powder in the hopper of a measure will also equilibrate with the ambient air, before it is returned to the container.

Wayne