I am having a rousing discussion with a close reloading friend. He thinks that mixing 2 different lots of the SAME BRAND POWDER is ok and safe. For example mixing 2 different cans of Unique with different lot numbers. In particular we are talking rifle loads. Specifically FMJ and match grade 5.56.

I don't feel comfortable doing it and don't feel it is safe. He does, what's your input?

i'd contact the manufacture + inquire - i have done it putting a small left over amount into a new can + shaking it well , but i was much younger then -

If I have a small amount left in the hopper when I'm changing calibers and powder, and all I have is a new canister of the same powder, I'll pour them together. Shaking to blend that small amount with a full pound cannister OF THE EXACT SAME POWDER, does not keep me awake at night.

I know different batch numbers can vary a little from batch to batch, but I doubt it will ever be enough to mess up my loads. I'm not a bench rest shooter, so it won't matter in that regard. And I doubt it will cause an explosion.

Everyone will have their own opinion of course, so if little things like that make you toss & turn all night, and you'll likely decide to throw the whole batch out in the morning, you best not do it.

Curious what the general consensus is, because I know there will be many on the other side of this. Good question.

A long time ago I was told never, ever mix powders. The same or not, I just load all I can from the canister and then move on to the new canister. Any left over goes in the wife's flower bed.........

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USMC 69-93 Combat Pistol Inst.

If a small amount, I will mix to the new container of the same powder but.....

When loading steel pellets for ducks...........

Alliant Steel powder lot to lot could have a big jump in fps.........
so you did not want to mess up the slower/lower fps jug, by mixing it, to the better powder !!

If you have a chrony this can be found out but some just have to work with loading manuals and never know the difference, that may be taking place.

I'll admit, with small amounts left over, I will mix with the next new container. It's usually such a small amount, I don't see how it could affect the next loading session. I always check my powder measure/grain weights when I start a new powder container/lot anyway.

Small amounts of pistol powder, I will mix and shake. I've not seen my favorites change in many years. Rifle and shotgun, no.

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Heavily armed old man.

I do it all the time.

For pistol shooting, as others have said, I run a can down towards then end and then dump the fresh powder into the hopper on top. If I was going to switch calibers and had only a little left I would not feel bad about dumping it into the top of the new jug (just make sure you dump it into a can of the same power) I do not normally run my pistol reloads near max so I do not feel the need to recalibrate my load data when switching powder jugs.

For precision rifle, I am a member of the OBT school of thought. In this case we are calibrating our load to the rifle barrel, taking into account powder burn rate as well as the ambient temperature. I want a large batch of powder, like 16# to do my load development on and then continue shooting with, so if I can only get 8# jugs then I will dump them together and mix them up before I do my load development.

This is what I do.
I know multiple other long range shooters that do the same.
It is probably not SAAMI compliant.
I do not advocate that you should do this.

Do it all the time no problem. I once asked my late friend Ed Matunas a ballistics expert if it was a problem he said absolutely not an issue.

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Len

I have always done it. You have 1/2oz in the bottom of a 1#, much less 4# can, adding that to a diff lot means nothing. Even in precision rofle, just neber seen tje diff on paper or over the chrono.

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NRA Cert. Inst. IDPA CSO

Geeezze Fred;

you better step away from the bar and have a cup of coffee..............

that typing is pretty bad.

I know I'm not supposed to but I have for many years. I used to do load workup with every new batch of powder and ALWAYS ended up at the exact same load prior to the new batch.

I couldn't tell you exactly how many pounds of Sport Pistol I have burned but it would be at least 40. Same goes for H110. Some big jugs, some single pound bottles. I have never had an issue.

As for my PRS rifles, I bought a large quantity of powder and mixed it all together ONCE. Never again. The jugs the powder are sold in are way to convenient on many levels, mainly with static electricity. So I just keep the powder hopper topped up and if there is a new bottle of powder, I take the time to verify my zero with the new batch. Haven't touched my adjusters for YEARS.

FWIW, YMMV, my $0.02

Unless you are sorting your brass, primers, and bullets, by lot number, it is probably a waste of time.

And then there are temperature and humidity.

Have always done it with handgun loads but never rofle loads- shotguns that as well. So far so good

Been taking spelling lessons from Fred?

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USMC 69-93 Combat Pistol Inst.

Years ago when many of us started loading ammo I did not mix lots. When we(me) were much younger Lots of powder could have a fair amount of difference. Today's quality control gurus have gotten this powder stuff down to a real science and most lots are just repeats of the previous lots... I only mix smaller amounts with another can. And then I shake it fairly well so it is mixed. Rifle pistol and shotgun powders when you only have an ounce or so left....not much to change the load anyway. Usually more than the difference you may create with round to round differences. The guy at Hodgdon told me this when I did the shot show quite a few years ago.. Gotten better sinceWhy throw 6 to 10% of the powder away??

I started reloading in 1967 and don't remember any dire warning about mixing the same powders . Just don't mix different types of powders .

my common practice when running low on say Unique was to buy a new bottle and pour the remaining 1/4 to 1/2 cup of old Unique into the new bottle and turn it around a few times to mix new with old .
Nothing bad has ever happened ... to be honest I do this with all the powders I use ...lots of pistol powders have gone through my reloads .
Since I've been doing it for 53 years ...I either fail to see the danger or the Good Lord does look after children and Foolish Reloaders .
Gary

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Certified Cajun
NRA Member

No. Never.

And for a very, but really very, good reason. One of the powders I use the most, Vectan BA9 is inconsistent from lot to lot. I was told so in advance. And realized it was true when I opened a new lot and found out that the load I was using before (reliable accurate and mild), was still accurate and mild(er) but not reliable anymore.

Edit. Forgot to add. Point of impact was not the same either.

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Expect the unexpected

I try to "load through" the end of a can by pouring new powder on top of the previous lot in the powder measure, and then loading enough to use up whatever was in the hopper from the older lot.

This way I'm not constantly carrying-forward powder from each lot. In theory if you just mix the old with the new each time, some from each lot may accumulate in the leftover. I'd rather just deal with two.

But as I said...in theory. For years, nay decades, I just mixed (well ) the leftover with the new.

A tiny bit of powder (a few oz), diluted in a another can of 16 oz or more and shaken will not make a hill of beans difference,

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Still Running Against the Wind

So true. been doing it for over 40 years. No big deal. Yet some people are really besmirked by it.

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S&W Accumulator

Just a thought; I have read, on a couple different occasions, that powder manufacturers hold their powders' performance/specs to 4% of the original specs for the powder. So, in my thinking, unless a powder has undergone a drastic change (and is not renamed or highly publicized)my lot manufactured in 2000 will be within 4% of the same powder produced in 2020. And of course, my accuracy and velocity testing is done with a new lot and mixing has never shown any wild swings in performance. Yeah, I'll pour the ounce left in the bottom of one jug into the new jug...

Depends on the kind of accuracy you're aiming for.

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Expect the unexpected

If what powder is left in a can will not produce my next reload - it gets dumped in the yard. Just not worth a problem to be too cheap.

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S&W factory revolver armorer

For loads up to midrange I don't worry about mixing the same powder from different lots. For loads approaching maximum I don't and I work the loads back up for a new lot.

With that being said, if you're unwilling to mix different lots of the SAME powder, are you using the same charge weight for the new lot as the old without working up the load again? I don't see any difference myself.

I would be concerned with mixing if it's a max load. Looking at reloading manuals I see the same powders labeled differently, i.e. Win760 and H414, have different max loads. Win760 and H414 are the same powder, just labeled differently. Why the different max charge? Because the tested powders came from different lots.

First question is what do you do when you get a new batch of the same powder? Do you Re-Work up loads or not? Do you use some type of power thrower to charge your cases or do you weight the powder.

For pistol powders (And shotgun powders) if I get a new batch of powder that is from a different lot, I check the weight I get by volume against what I have from a different lot. So say, you XXX bushing throws 1.6 grains of Bullseye and you new lot get the same charge weight from the same busing than I don't worry about it. Run out the old or mix. But if there is an appreciable difference then not only don't I mix the powders, but I run some additional load work ups.

Bob

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Sag Harbor & Manhattan, N.Y.

I used to do it all the time when using W296 and H110.
Having been told by Hodgdon they are the exact same thing, I even mixed those together when running low.
Never noticed any problems but ran mainly just one load.
24 gr. 296/110 - 240 gr. bullet - 44 magnum.
I have moved away from ball powder altogether but will still mix the end of one canister with the next one for revolver loads.
Most of those are from the same lot however as I got as much as I could during/after the big shortages.
I will NOT mix similar powders I know to be different like the 4198's 4227's where H & IMR do not have the same exact properties.
H4227 is gone anyway but I have both 4198's and they even look different.
I find H4198 to be a bit slower (and has temp. comp.) than the IMR version I started with in the 444.
I have also not mixed (yet) Universal from Australia and Canada but if only a few grains are left probably will.
Bottom line is, yes, I'll do it but with eyes wide open.

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NEMO
"Everything 44"

I have when loading 300 Win. Mag loaded 75 gr of powder. If the last of that canister held 67 gr, I would add enough to round up to 75 which would be around 10%. I would then load 10 cartridges from the next lot and check accuracy and chrono them against the known reserve when I next shot. I would label the last cartridge loaded as practice ammo as it was mixed.
With pistol powders the charges are so small I don't mind tossing 3-9 grains.

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Front sight and squeeze

If the load I'm using is in the low end spectrum, I will make a test batch with the same load and chronograph it, see if functions, if it's accurate and if has the same point of impact. And, as I said, with BA9 I never get the same results.

If it's near max load I'll work it up again. No biggie, and I like having 5 fingers in my right hand and want to keep it that way .

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Expect the unexpected

Precision rifle loading, no.

Plinking rounds, yep I'm guilty of not checking lot #'s before continuing.

I read the same book as the OP, but it has been one of those things that fell by the wayside over the years.

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GOA
USA Shooting Supporter

This! Plus 1.

About 30 years ago I bought a really nice powder measure with a micrometer adjustment. The first thing I did was to do a calibration curve with each powder that I was using, and then plotted it on Excel. In every case the Rsq. was .999, so I know the measure was quite good.

To this day, every single new lot of powder still fits perfectly on those curves. I am amazed at the consistency of powders. When I want a charge I just look at the data and it dials in 1st try.

If I ever tried a powder that was inconsistent, I would never use it again.

Oh yes, I mix them all the time...

I'm curious why anyone would use something inconsistent from lot to lot. How can you depend on your favorite load to work the next time? I confess, I've never heard of BA9, well frankly I've never heard of Vectan either. But I don't get out much. LOL!

There's a lot more folks admitting to mixing small amounts than I expected. I kinda thought I'd be more of a minority with my admission.

It depends on the kind of accuracy you're looking for.

Another perspective on pistol powders if you are talking percentages:
Throwing 10-20 grains into a 7000 gr. (or larger) canister then loading 7 grains into each cartridge
means you have around .2% of the old powder in there: 15/100ths of a grain.
That's less than the throwing error of most powder drops.
Most scales aren't that accurate either.
If you are dumping the tail end (one or 2 cartridges worth) of a lot into a full one you'll never be able to tell the difference.

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NEMO
"Everything 44"

What is “OBT” ?

Oh Boy! This thread is gonna launch into the outfield.
I'll take the first stab:
Obsessive But Thoughtful?

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NEMO
"Everything 44"

Meaning what, exactly? What is the accuracy standard?

I'm genuinely curious about this ... my 9mm PPQs all group 2" at 50 yards, I have multiple 629's that will pop milk jugs at 100 yards all day long or my PRS rifles that are all sub 1/2 MOA. All of these rifles and pistols have done these things for many years and none have ever run factory loaded ammunition.

I guess my accuracy standards are just too low or I have no idea what I am doing.

I always pour the last of a can of powder into the next and mix very well by shaking and rotating vigorously.

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dd884
JMHO-YMMV

This is what I also do. By the time I get to the bottom of a powder can, there's less than what it would take to make a single round. I can't see how 30 grains of powder of one lot could affect 7000 grains (one pound) of another lot, when they are the same type of powder.

For my part. Nothing close to 100 yards. Only 27(25 meters). But I have won and lost matches by one lousy point Sometimes on the very last shot.

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Expect the unexpected

I don't store them mixed. I do open and pour the next available different lot, same powder into the measure and just keep loading. So, technically I do mix.

Promo was the only powder that I ever even noticed a lot - lot difference with.
The difference was minor, but noticeable.

"Optimum Barrel Time". This is about as far off topic as we can get: Optimal Barrel Time Paper

If you are not a long range rifle shooter and also ~ 75% crazy then you can just ignore.

Powders that we buy for handloading are blended at the factory so that a certain given weight,(dictated by your loading bushings etc.), will give a specifically set performance. If your powder is in good shape you can in fact mix them as long as they are the same. Example, you can mix Red Dot with another Red Dot, Blue with another Blue etc. It is safe as long it is the same powder.

I am not a long range shooter but I could not ignore it either (maybe I am 75% crazy).
Thanks! I never would have guessed that acronym.
I find I actually have the PDF of that article I got from the RSI site (see below).
Barrel time is also how double rifle guys attempt to regulate a non-standard round.
This leads to the not so obvious solution of dialing back lighter bullets and hammering the heck out of heavier than normal ones,
trying at the same time to not blow up your precious rifle or self.
I also enjoy anything to do with internal ballistics; isn't that what we reloaders are here for?
Interesting stuff.
I sometimes wish I had gotten a barrel pressure strain gauge setup.
It's about the only style of ballistics lab equipment I never acquired.
Recreational Software Inc.

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NEMO
"Everything 44"