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# Powder lot number?

#15
01-22-2007, 10:52 PM
 Platinum Member Join Date: Sep 2004 Location: on the rifle range in Utah Posts: 2,704
Re: Powder lot number?

I guess I will have to be the stick in the mud and be the "one guy" who warns against this practice of mixing. Well, not so much a warning for safety (the safety points are obvious and self-evident) as for a warning about statistics. Two lots of the same powder might be fine for safety sake, but the math involved concerning statistics shows that is is physically impossible to mix two powders or two lots of powder in a 50-50 mix utilizing regular mixing methods. Only by individually taking one kernal from one and one kernal from the other and putting together would yeild a perfect 50-50 mix.

Now, with some powders (like Varget possibly) you have pretty good lot to lot consistency and the burn rate would probably be close enough that it would wash out fairly well with no considerable loss (or gain) in "quickness" of rate. But I have seen lots of RL22 and IMR7828 among others that were far enough off in burn rate to give disastrous results. If not disastrous, then highly unpredictable and inconsistent. Mostly because of the aforementioned problem of statistical mixing.

Buy 200 green beads and 200 red beads and mix them up any way you like and then pour half of the mix into another bottle and then count the resulting red and green beads. You would have to mix them several hundred million (possibly billion) to get one time that they actually came out a perfect 50-50. It's basically impossible unless you count out x green beads and equal amount of red beads and put them in together.

While I would feel safe mixing two lots of Varget together, I would find it too inconsistent to get good standard deviations in every string of shooting on a load that otherwise always has uniform combustion.

A few guys I know mix H322 and Benchmark together in a bottle and shake it up and then load it in 6ppc's. It works well for them, but I and others have noticed these fellas occasionally have those bad unexplained fliers from the rest of the group and they NEVER blame the powder mix. It is usually blamed on that puff of wind that mysteriously came across the field of wind flags without any of the flags registering it!

Bottom line: I won't do it. But to each his own. If you guys find an easy way to mix them in a perfect 50-50, you could retire the next day in the Bahamas!
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#16
01-23-2007, 06:35 AM
 Gold Member Join Date: May 2001 Posts: 923
Re: Powder lot number?

The fly in that 200 marble ointment is...

... take 7 tons of 50/50 mixed powder (half of the powder is white and half is black - like your marbles), and start pouring them in 1 pound cans. the chance of getting a 50/50 mix in ANY of the cans is millions to one... so by your thinking, we have to test every can of powder.

But it gets worse.

Take a one pound can of (now questionable) 50/50 mix, and pour 1/3 of it in a powder measure. The chances of the mix in the measure being the same as the mix left in the can are one million to one.

So we can't trust our powder measures.

But it gets worse (you knew that was coming [img]/ubbthreads/images/graemlins/wink.gif[/img] )...

Toss a charge into the case, and the chances of that charge having the same proportions of mix as the powder in the hopper...
... and the same as the powder in the can...
... and the same mix as the powder in the bulk mix...
... is about eleventy trillion to one.

Aren't you glad you tossed this issue in the "mix". By the way, when you go to a diner, DON'T put ketchup on your burgers, cuz every night, the waitresses put the leftover ketchup in bottles to fill them, so the ketchup will not be the same as it was yesterday.

Don'tcha love these "theoretical", anal retentive compulsive, go nowhere debates??

Now... if you took 500 black cats, and 500 white cats, and tried to heard them... when you got where you were going, what would be the percentage of black cats to white cats? [img]/ubbthreads/images/graemlins/wink.gif[/img] [img]/ubbthreads/images/graemlins/wink.gif[/img]

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#17
01-23-2007, 07:12 AM
 Silver Member Join Date: Apr 2006 Location: Chickasaw Point, SC Posts: 206
Re: Powder lot number?

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Now... if you took 500 black cats, and 500 white cats, and tried to heard them... when you got where you were going, what would be the percentage of black cats to white cats?

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#18
01-23-2007, 07:46 AM
 Gold Member Join Date: May 2001 Posts: 923
Re: Powder lot number?

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I hear that!!

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LRH member #23
#19
01-23-2007, 09:26 AM
 Platinum Member Join Date: Sep 2004 Location: on the rifle range in Utah Posts: 2,704
Re: Powder lot number?

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so by your thinking, we have to test every can of powder.

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And that is exactly what they do at the factories. That is how they arrive at the lot numbers. Obviously the powder in any given can is going to be a blend, but they segregate it by lot number so each bottle with the same lot number is as close to being consistent as possible so that the reloader can count on his specific lot being the same burn rate as his last can of that specific lot. If this were not so, working up a load for a gun with any powder would be a crapshoot.

As I said, mix if you want. But I will not because I have too much riding on each shot. If I find a lot of powder that works, I scour the countryside to find more of it. If I can't find another bottle, then I start from scratch on load development with a new lot.
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#20
01-23-2007, 09:44 AM
 Gold Member Join Date: May 2001 Posts: 923
Re: Powder lot number?

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so by your thinking, we have to test every can of powder.

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And that is exactly what they do at the factories. That is how they arrive at the lot numbers.

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No it is not. They do NOT test each 1# can.

The blend several tons and test that "lot number", and each can poured from that "several tons" bares the same lot number. - very silly. You have no idea of how powder is manufactured and distributed.

[ QUOTE ]
Obviously the powder in any given can is going to be a blend, but they segregate it by lot number so each bottle with the same lot number is as close to being consistent as possible so that the reloader can count on his specific lot being the same burn rate as his last can of that specific lot.

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What happened to your white and black marble theory??

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If this were not so, working up a load for a gun with any powder would be a crapshoot.

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So you start all over and work up loads with each can of powder with a different lot number??

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If I find a lot of powder that works, I scour the countryside to find more of it. If I can't find another bottle, then I start from scratch on load development with a new lot.

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Wow... you must have a LOT riding on each shot.

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#21
01-23-2007, 06:04 PM
 Platinum Member Join Date: Sep 2004 Location: on the rifle range in Utah Posts: 2,704
Re: Powder lot number?

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No it is not. They do NOT test each 1# can.

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I never said they test each 1 pound container. I meant that they test each lot for burn rate against a control lot. Obviously they wouldn't test each 1 pound container. They do however take random 1 pound containers and test them for quickness against their control.

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The blend several tons and test that "lot number",

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They blend several components of the powder into big batches, not several lots of powder to attain the desired burn rate.

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very silly. You have no idea of how powder is manufactured and distributed.

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Pretty bold statement. Especially considering the fact I have spent several hours conversing with different powder companies about their procedures over the years. I might not make powder for a living, but I do deal with it for a living so I have actually learned a thing or two about it. Saying what you said is pretty unfounded and the way you went about it wasn't very civil. I was merely trying to point out a few things based on my fairly extensive knowledge of the subject and just because it was against you're personal practices, you denounce me as unlearned.
That is not very smart in and of itself.

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What happened to your white and black marble theory??

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Actually, is was red and green beads but we'll go with marbles if you like. Thanks for your attention to detail.

When I say blend, it is a blend of components and deterrents, NOT BLENDS OF LOT NUMBERS. A lot is blended to get the appropriate burn rate and then tested against a control lot. It is then segregated for the reloaders safety and information. So that particular lot is x burn rate and can be distinguished from another lot which will always have a slower or faster burn rate. The blended parts are accounted for and labeled in this manner so as to help you, the reloader. If you mix your lots in any way after they leave the factory, you have in effect, changed the advertised burn rate of that powder!! Can you not see this!?

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So you start all over and work up loads with each can of powder with a different lot number??

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<font color="red"> ABSOLUTELY!! </font> Every precision shooter I know does this because of the variation in lot to lot. If you don't start over when buying a new lot and are running a hot load, you are asking for disaster. This is basic reloading 101 and I can't believe we are even talking about this point.

ME: What is Hodgdon's official stance on mixing powders?

HODGDON: DON'T EVER DO IT! NOT EVEN IF YOU THINK YOU KNOW WHAT YOU'RE DOING! DON'T MIX POWDERS AND DON'T EVEN MIX DIFFERENT LOTS OF THE SAME POWDER! NEVER, NEVER, NEVER!

ME: Why not?

Hodgdon: Because you will change the burn rate of the powder and that could be unsafe! Even if you do it safely, you will never get good performance or consistent performance from the powder.

Me: Well what if you took one kernal at a time and mixed them in a perfect 50-50 mix?

Hodgdon: You would successfully change the burn rate again and that can be dangerous. And even if you did it successfully and had no problems, the next time you went to mix and had to get a new lot of either one or both powders, your new mix would have a different burn rate than your previous mix! So it would be totally against your efforts any way.

Me: How much could mixing powders change the burn rate?

Hodgdon: Well, in our lots, we have plus or minus 3% to 6% variation in burn rate between lots even with the best components and manufacturing processes. So if you mix two powders and one is on the high side of 6% and the other was on the low side of 6%, your new mixed powder could be changed as much as 12%!

ME: WOW, I can see how that could be disastrous! That is like going from H322 to H4350 in burn rate!

Hodgdon: That is correct. Very risky.

Me: I used an example of different color beads to illustrate the complexities of mixing the perfect 50-50 batch. Would you agree this would be a fair example of what "do-it-yourselfers" are doing by mixing the powders at home? It is statistically impossible to mix them evenly.

Hodgon: Yes, that is a good example. You will never mix anything evenly and home "mixers" don't possess the proper equipment to safely test and control what they are doing to the powder. When it leaves the factory, you know that our engineers and techs have tested it with state of the art methods and as long as you pay attention to the lot numbers and always start from the bottom when working with a new lot number in any gun, you will be safe.

ME: What makes a lot of powder a lot of powder?

Hodgdon: We have a control lot of powder and we test it against new batches to see what the differences are. The lot is the result of this test. Our production batches are made by ADI {I think he said this was Australian Defense Industries} and they will mix known components of deterrent or nitrocellulose to get as close as possible to our standard control lot. They come close, but it is nearly impossible to get it exact every time. It happens by luck occasionally.

ME: So mixing different lots of Varget together to get a desired burn rate does not happen?

Hodgdon: No. ADI mixes components together that are not quite Varget to get the desired burn rate. That is why the 3%-6% variation can occur.

Me: What do you think of guys mixing H322 and Varget together to get a custom blend for their 6ppc's?

Hodgdon: Well, you can't stop them from doing it but we suggest not doing it even if you are a serious reloader.

And then Catshooter says:
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Wow... you must have a LOT riding on each shot.

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Why yes I do. Every shot counts. Perhaps we should have thrown together a Heinz 57 mix into my hunting rifle to kill that cow elk at 1203 yards with one shot a few weeks ago and we could have killed it at 2 miles instead. If only I had known more about powder at the time! Dang it! Well, maybe I'm dumb and the engineers at Hodgdon are dumb so let's see.... if we take a few kernals of Red dot, throw in a few of Retumbo, then add a sprinkle of 7828 we could come up with the ultimate 300 ultra mag load!! It would give standard deviations in the zeros all the time and we could really reach out and shoot the neighbors kitty cats across the yard all day long! [img]/ubbthreads/images/graemlins/grin.gif[/img]
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