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Discussion Starter #1
How much variation have people seen with different powder lots as the only variable?

I have records that seem to show as much as 150 fps differences that I cannot be sure are due to only powder lot# variation. How much difference does powder lot make? How close to "max" do I need to be, to make it necessary to always test a new lot #?
 

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I'm not sure if there is a standard, although 3-5% max variation seems about right. Reducing your powder usages (one powder for multiple cartridges) and buying in bulk whenever possible is the best way to eliminate lot to lot variations.

Its fully possible for no variation to exist as well. I know Alliant tests every lot against a known sample for consistency. Hodgdon buys powders from multiple manufacturers and might not have the same standards.
 

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I have used some powders for close to 40 years. I think IMR powders have changed the least, Hercules/Alliant has changed/dropped so many, it's hard to tell for rifle, the flake powders have changed enough to be careful with data. Accurate powders have skipped around a lot, but they haven't changed much for the ones I use.

Last year to this year, most are the same. Lot to lot has never been an issue, but when they are bought/sold, or move manufacturing, it's like a restart. Be careful.

Another "it depends".
 

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With the powders I use most, I see very little variation lot to lot. Exception to that is with some that have been on the shelf for many years. Sometimes the makers/owners have changed.

I remember posting a thread here once about a significant change of an IMR powder when I changed lots.

Is allways best to err on the safe side in my opinion. Not hard. Is part of being a handloader.

Cheezywan
 

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mattsbox99;I know Alliant tests every lot against a known sample for consistency. [/QUOTE said:
Here is a copy paste from Alliants website. It seems that they try to blend every batch to get it as close to the previous batch as possible. I use a lot of their powders in pistol and shotshell loads and have never had a problem with inconsistency.


Our Mission: Premium Performance, Consistent Quality

Every container of Alliant smokeless powder is backed by a century of manufacturing experience and the most exacting quality control procedures in the industry. We check and control chemical composition, the shape and size of powder grains, even the propellants' density and porosity. We send samples of every batch to our ballistics lab, testing for burning speed, among other things. Then, after blending batches together for exactly the right ballistic characterisitics, we use our advanced computerized equipment to test again.
 

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Our Mission: Premium Performance, Consistent Quality
Having used Alliant powders for the last 40 years, the only way to notice the differences is to use powders from a widely spaced period of time, with the same components. They've changed, some quite a bit.

My last big buy was from a shop going under in the 80's. I picked up several 4lb containers of Red Dot, Green Dot, Herco, and a few lbs of R12/15. R12 is obsolete, but the rest are not the same in recently manufactured lots. Some are hotter, some are milder. The difference is most noticable with an autoloader, shotgun, rifle or handgun.
 

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There are two kinds of changes with powder: there are the usual lot-to-lot variations and then there are formulaic changes.

Lot-lot variation is always held to less than 5% of the burn rate standard for that powder, and rarely will a company release a lot that is more than 3% off without re-blending it.

Formulaic changes are not so predictable. When a company comes out with a "New and Improved!!!" version of a powder, it may or may not hold to the original performance specifications. Reliable testers say that the current Alliant 2400 (for example) is about 6% hotter than the original - and that is before lot-lot variation. So it is possible for a given lot of 2400 to be either almost the same as always, or as much as 10% hotter. That could be quite significant, since 2400 is often used in maximum-power loads.
 

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I can attest to the change in 2400. I was using 22 grains of 2400 to propel a 429421 from my 44 mag RH when I first got it some 25 years ago. Now that can of powder is since long gone and recently I bought some more and loaded it the same with the same bullet. HOLY COW!!!!Even Lyman's 48th says it's the same but it's not. I'm down to 18 grains and still pushing the 429421 at over 1400 fps.

RJ
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Powder does vary from lot to lot, some.

But barrel temperature is a very strong variable. You really can't compare two lots of powder unless you control that. Ammunition temperature is also important, but not as important as barrel temperature.

So if a new lot of powder produces an additional 50 FPS, and if you haven't controlled barrel and ammunition temperature, you don't know whether the effect you saw was from temperature or from a difference in the powder.
 

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I use a "medium load/charge" to compensate for lot-to-lot variations in powders. For example if they list 50.0 grains of a certain powder as max.; I would use 45.0 to 48.0 grains depending on the powder.
 

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Discussion Starter #11
Thank you to all. I think buying in big lots, and testing new ones is the only safe way I can go if I am at tested maximums. I think I knew that; I was hoping someone would say it was a complete waste of time. :(
 
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