Powder Mixing (oldie but goodie)

[mehavey]

Let's say that I have 5 pounds of IMR4831 bought over the last 2-3 years, and all kept in dry/cool environment (i.e., pristine)
And let's say that (for any number of strange reasons) I have three Lot#'s involved, and all containers range from 1/2 to full up.

Given that the powder plant establishes it's canister controls by literally mixing powders from sometimes significantly different lots:

Why would (I) not be able to reasonably do the same thing (let's say 10 minutes in a classic Thumlers Tumbler) to get a single
4½-lb "Lot" of uniform powder ?

[Jimro]

IMR powders are known to be very consistent from lot to lot, so odds are you would never notice a problem.

If I were to do it, I would load up a ladder test from each of the 3 lot numbers with the same charges and bullet.

Then I would test to see if the same charges all grouped in the same groups throughout the ladder range.

If you get even groups through the three lots, I'd feel much more comfortable mixing the powder. If you got a lot of spread between lots with the same charge weight, that would give me some serious concern.

Safest course of action is to just use up the powder as it sits now. In the end you will still have the same ammount of powder as if you mixed it.

Jimro

[mehavey]

IMR powders are known to be very consistent from lot to lot...

Noted and agree, ....
as well as expect most all classic Hodgdon powders of late. (While excellent within a single Lot,
however, I wouldn't ever combine different lots of Accurate on a bet.)


That said, I'm using volumetric measure* rather than weight to load relatively low pressure 175gr
match ammunition in the 30-06. I'll try a 20/20/20/20/20 mix to get a "pound" out of
the five separate 4831 bottles to run a volume measure test and report back.


* (Last weekend at ~70° I was getting 2,528±04(four)fps and 5/8" out of that Harrell's measure.
I admit to being impressed.)

[BigD_in_FL]

I would skip the tumblings and just blend them together in one container where you can shake them enough to blend

[buck460XVR]

I would skip the tumblings and just blend them together in one container where you can shake them enough to blend

Same here. When loading high volume handgun rounds, I actually will mix a new jug into whatever I've been using when it's about half gone. Doing this will make any variance between the lot numbers about half of what it would be if left to themselves. Difference is so slight that I don't bother to rework loads.....but then I don't load to max. It's a trick old painters used when having to use paint from a different lots in the same room. I used to work back up and chrono, but after a while found the variance from lots when doing this is no more than the variance from different batches I've loaded at different times.

[serf 'rett]

I've been eyeballing two new 4# containers of Power Pistol from different lots and wondering about mixing the two with the idea of only needing to work up loads from one "blended" powder batch instead of needing to retest when moving from lot to lot.

And if I'm going that far, why not throw in that third 4# container in the mix too? Hummmm......

And that dear readers is an indicator of reloading addiction - when the new ideas never stop and the perfect load is always just a "few more" tests away.

My question is how does one end up with 5 opened bottles of the same stuff?

I'm quite sure I would have mixed them a long time ago.

[Slamfire]

I have done this, mixed the bottom on one can (about ¼ cup of powder) into a pound of another lot. Have done with Alliant Unique, Bullseye, 2400 and IMR 4895/4064. No problem to date.

However, I would not do it with Accurate Arms powders as their powder suppliers change. One lot would be made in China another in Czechoslovakia. I suspect Accurate Arms, and probably most of the powder procured this way, is purchased under a performance specification: that is the powder has to meet some basic physical dimensions and a pressure curve requirement. Might be some environmental considerations too, but who knows. Performance specs don’t go to the detail of telling the vendor what to put in his powder.

Powders are chemical mixes, they have burn rate inhibitors and I don’t know what else, and it is possible that Vendor’s A powder mix will react or burn in a strange way if mixed with Vendor’s B powder.

And that is the risk you face mixing powders, you assume that they are all identical 100% chemically, and that may not be true.