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Old July 12, 2012, 09:42 PM   #1
grisbald
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Mixing Powders Question

I know that mixing powders of different kinds is a big no-no, but what about the same one? I've got 2 1-lb containers of Varget, and I bet I have maybe 5-10 loadings in one container, and the other is full. Is it ok to mix them both in the powder measure for my next loading session?
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Old July 12, 2012, 09:46 PM   #2
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I do that all the time. I'll add the last little bit of one container into the other than give it a good shaking. If my loads are at or near max I'll also do a quick load work up to double check pressure, just one or two rounds at 90% and 95% max.
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Old July 12, 2012, 09:52 PM   #3
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Yes go ahead . As long as you mix them up real good all you did was uniform 2 lbs. A stated work your load back up again,but you will be fine
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Old July 12, 2012, 11:59 PM   #4
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I always mix the last of one bottle of say Varget with the next bottle of Varget I open. Some people who can't find an 8lb jug or a bunch of pounds of the same lot will mix several new lbs of the same powder together to use.
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Old July 13, 2012, 12:54 AM   #5
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Powder companies and powder Nazis will say to never do it, but I mix different lots of the same powder all the time.
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Old July 13, 2012, 05:57 AM   #6
Salmoneye
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There were 'duplex' powder loads listed in various manuals in the past...

Paul Mansfield was one such proponent...

I am NOT suggesting anyone try duplex loads...

Simply pointing out for historical reference...
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Old July 13, 2012, 09:41 AM   #7
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Hodgdon says lot-to-lot variation in Varget burn rate is currently held to ±3%, so your new purchase may require you to tweak your loads to get to best performance equivalence. Simply tossing the old on top of the new could get you some bad loads because of as much as 6% difference in burn rate between the two lots is theoretically possible. If the old powder isn't very old and you blend the two very thoroughly you should not have a problem, but you will have to test loads with this new blended lot to look for matching performance.

What I usually do instead of blending is load up the last ten or fifteen rounds of the old powder, then do the same number with the new powder and head to the range. I fire over the chronograph alternating between the old and the new. That evens out the effects of fouling accumulation, barrel temperature and changing ambient conditions, if there are such. At home I separate the two sets of data manually and look for a difference in the average velocities of the two to learn if I need to adjust the charge of the new lot of powder to match the old. This has happened. Some of the early Varget, in particular, was slower than some of the current stuff. I don't think Hodgdon's QC was as good when Varget first came out as it is now.

The only other thing to watch out for in blending is age. If the old lot you have is old enough that it might begin to break down, putting it in with new powder can accelerate aging of the new powder. That's because acid breakdown products tend consume the stabilizer at the surface of the newer powder, accelerating the start of it's own breakdown. If I were mixing powder I would never mix twenty year old powder with new for fear of that happening. Ten year old powder wouldn't worry me, though.
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Old July 13, 2012, 11:20 AM   #8
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For 'match' performance I would agree with Unclenick. But for me, when I have a little bit of Unique/4227/Trail Boss (for example) left in the bottle, I just pour it into a new bottle. No mixing. For what I do, the little variation that 'may' be there isn't going to matter for my caliber of revolver shooting.
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Old July 13, 2012, 11:41 AM   #9
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I don't worry about mixing up the last of one keg ...into another keg of the same powder...especially if they were both relatively recent purchases ( I'd just shake it up after I mix them together).

Now, if one keg was 12 yrs old...and the other one was brand new..I wouldn't mix them...and I would re-check my loads ( kind of the way uncle nick suggested) - or at least test fire them without a chronograph..starting at the min ..and work my way up to near max ..before I settled on my "goal" powder drop for that caliber.

I would also be more cautious if anything had changed with the powder company ...like they were bought out in between the time the 2 kegs were produced.
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Old July 13, 2012, 02:31 PM   #10
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I have mixed powder containers when I have had half a cup to quarter cup of powder left in one can and mixed it with a full can. To date no problems, but there are risks.

There are only a few powder manufacturers but the one that made your lot A may not be the same one that made your Lot B. Therefore you do not know if the powders are chemically identical, and they are probably not. Differences in composition of those powders could cause burn rate issues.

Accurate Arms, as an example, has used a number of different vendors, I have used Chinese AA2520, Czech AA2520 powders, I would not mix them even though the name on the bottle is the same.

Don’t mix old powders with new. The rule of thumb for powder lifetime is 45 years with single based and 20 years for double based. You mix old gunpowder that was aged in hot conditions, or is just old, ready to be tossed, with new gunpowder, there are a number of issues and they are all bad.
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Old July 13, 2012, 02:32 PM   #11
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I can see mixing two new cans together to uniform them, but I dont see the point of mixing the last bit of the old into the new... Either way if you are at max loads you should to do a load workup.... I am 2gr below max with my hunting load, so I would rather just shoot the last of the old power, which is a known good load, and then try the new power, and do a workup if it doesnt shoot the same.... I would rather have those last 10-15 rounds be a known entity personally....
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Old July 13, 2012, 03:17 PM   #12
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Rifle powder I wouldn't. It's too much work to test and get that perfect load and then mix and it may be alright or it may not. For me Varget I would not. But you may not care about every little detail either.
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Old July 13, 2012, 04:56 PM   #13
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Not following some of you guys...

Do you really do new load development every time you crack open a new jug of (Varget or whatever) because there might be a tiny lot variation?
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Old July 13, 2012, 05:32 PM   #14
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I don't use Varget specificially but if I'm at max load then yeah I'll make a few rounds working back up. Doing this once every 4-8 lbs of powder really isn't that big of a deal in my mind.
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Old July 13, 2012, 06:02 PM   #15
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" ... Do you really do new load development every time you crack open a new jug of (Varget or whatever) because there might be a tiny lot variation?...."


Yes, I really do ...but it isn't that big a deal ( and I reload from 8 lb kegs ) so it isn't like I'm opening a new 8 lb keg every month...in fact, since I use one powder now for all my handgun loads in 9mm, .40, .45acp, .38 spl, .357 mag and .44mag ( Hodgdon Universal ) ....an 8 lb keg will probably give me about 200 boxes of handgun ammo ( depending on how much 9mm is part of the mix / and its a lot ).

I just load a partial box...5 rounds at min, go up 0.1 grain and load 5 more, etc until I get to 0.1 grain below published max....take them to the range and test fire them...see how they feel / any changes in accuracy --- and a box of my previous loads....see if there is any difference.

I probably open a new 8 lb keg of Universal about every 4 - 6 months...and I just do my "load checking" ...on whatever handgun caliber I'm loading at that time ...( 75% of the time, I shoot 9mm or .357 mag ) probably.
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Old July 13, 2012, 06:26 PM   #16
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i use Varget in my 223 only. I only buy 1 lb at a time,but i never change my load with a new lb. 25.5 is where i go.It is below max so i don't worry about it.
As for accuracy,I have never noticed a difference from lb to lb. Now with the 308 i use H-4895 (also buy in 1 lb containers). I go through a lb about every other week. or more. ( i shoot a lot ). I still never work up my load over and still have not noticed any change in accuracy either. Was on vacatio0n last 2 weeks now and have used 2 lbs of H-4895 in one week. Never a issue.

For those that do rework your load,, Have you ever had a issue?. I really intrested here as i never have. Do you always come back to where you were with the other container?>
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Old July 14, 2012, 04:41 AM   #17
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Quote:
Originally Posted by tobnpr
Do you really do new load development every time you crack open a new jug of (Varget or whatever) because there might be a tiny lot variation?
No, I don't. But, I'm not a match shooter, nor a competitor, nor even a benchrest guy. I'm not looking for the ultimate accuracy bughole group, just good dependable hunting ammo. I don't spend a lot of time at the bench, preferring to shoot off the hood of my pickup truck. So, lots of the loading practices of the guys who spend time chasing other things don't interest me. I also don't load to max charges, preferring to stay down in the mid-range. Accuracy matters to me, but only to the point where I can be reasonably sure that my bullet is going to whack what I aim at.

I'm not going to talk bad about guys who chase the ultimate accuracy from their rifle. That's how we learn things and I've learned a lot about reloading from this forum. There is lots of room in this hobby for guys like me, who simply want better ammo than we can buy at the store, and to save money on our ammo. I've got two or three pet loads that I've worked up over the years, and they never fail to satisfy. I'm also toying with new loads constantly, loving to tinker with such things. But, no, I'm not going to weigh brass, nor work up loads just because I open a new pound of powder.
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Old July 14, 2012, 12:08 PM   #18
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Quote:
Not following some of you guys...

Do you really do new load development every time you crack open a new jug of (Varget or whatever) because there might be a tiny lot variation?
I dont, but only because I am 2gr below max with my hunting load. I DO however only make 10 rounds with a new canister until I can test it to make sure its still accurate..... My .308 being my hunting rifle I dont go through cans and cans of it, Going from my fist lb to my second lb, I saw no difference in groups using the same load. Nearing time for my 3rd lb, but I plan to make up my ammo for this years hunting BEFORE I buy a new can, just in case. I wouldn't dream of mixing the last of my current can into a new can and then taking that ammo, untested, hunting with me....

If I were right on the bleeding edge of max load, I would make up some rounds starting 10% less, and work back up to my load looking for pressure signs... Thats just good policy, because you never know...
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Old July 14, 2012, 12:31 PM   #19
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I was asking because I never knew there could be that much variation between lots. I load on a progessive- so it's not uncommon for inconsistencies of a tenth, or two... sometimes three

So, powder inconsistencies only add to the "mix".

But, it's a compromise I've chosen because I load for my two sons, as well as myself. Last weekend it was .308, 7mm.-.08, 6.5 Grendel, 7.5 x 55 Swiss, and .223...

Whew... 550 rounds... I'd be drooling in the corner if I was single-loading and trickling up. Yes, we do shoot long range- and I'm sure the inconsistencies "cost"...

Some day, someone will invent a press with the speed of a progressive, with a high-speed electronic dispenser accurate to less than a grain
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Old July 14, 2012, 12:54 PM   #20
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Quote:
Hodgdon says lot-to-lot variation in Varget burn rate is currently held to ±3%, so your new purchase may require you to tweak your loads to get to best performance equivalence. Simply tossing the old on top of the new could get you some bad loads because of as much as 6% difference in burn rate between the two lots is theoretically possible.
That theoretical difference is only when the two powders are still in their original containers. Once you mix them, you will never get a greater variance from the mix then of any one alone. If you have a pound of +3 and a pound of -3, thoroughly mixed, you end up with a powder exactly at the manufacturers targeted burn rate. If both powders are +3 and you mix them, you still end up with +3, not +6. In other words, you can not end up with a "bad" load simply by mixing them. Yes there may be the same small difference in velocity/accuracy/pressure as between lots themselves, but it will not be any greater and no more dangerous. In theory, the equaling out by mixing them if there is that great difference will make the end result closer to manufacturers intentions. How much this equals out is dependent on how much volume there is of each powder.
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Old July 15, 2012, 04:05 PM   #21
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Tobnpr,

The rule of thumb with a new lot of just one component being substituted into a properly developed existing load for your particular gun is to drop the charge weight 5%, then work back up while watching for pressure signs. That can be done with four rounds if you know how to watch for pressure signs. Having a chronograph tells you if those rounds are are going to go over the velocity of the previous lot or not, and using that as a simple limiter is convenient.

If you have a rifle load that's centered at a good sweet spot, you can usually vary the charge somewhere around ±1% before you risk getting outside the sweet spot. Changing powder burn rate ±3% is equivalent to closer to ±2% change in powder charge weight. So it's a little bit much to expect many sweet spots will be that wide (though not unheard of-they can also be a little less wide, but ±1% is kind of typical in medium power rifle loads).

So, lets suppose you had a lot of powder that was -3% of average burn rate and you developed the perfect sweet spot load with that lot and identified it's center so your powder measure could throw ±1% and you wouldn't need to worry about it. Then the next lot of powder you bought was +3% in burn rate. Well, your powder charge would need to be down 3½%-4% or so to get the same velocity and have about the same barrel time as the previous load so you stay on the sweet spot. Note that this velocity match approach only works with the same type powder. If you had a different type, even with the velocities matched, the barrel time could still be substantially different.

The 5% rule is just for a little extra margin. Note that it only applies to the same load already developed for the same gun, and if you change more than one component or you change guns, then the 10% rule applies until you prove to yourself you're OK with less change than that.
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