Thoughts on mixing powder lots?

[Oldschool280]

I have three seperate 1 pound bottles of mrp, i was thinking of blendingnthem
All together so i do not have to make adjustments for every bottle. Anybody doing this?

 

[Darkker]

Lots can vary by 10+%, I've got the pressure trace proof.
If you don't know how those lots line-up in terms of burning rate, it's a very very bad idea.

 

[MNbogboy]

I have always done this for the very same reason ...During the shortage a few years ago it was hard to find 8 pounders and often hard to find anything within the same lot in numbers above three or four one pounders so the mixing became common for me...I still blend all single pound bottles of the same lot number when thats all I can get....At the end of a batch the small amount of leftover will get blended into any new lot that I buy.

Some say no....But after over 50 years of reloading I'm still here...

 

[RT2506]

I do it. I suggest that if you have a pet load with such powder that you back off and work back up with a new blended batch.

 

[Kansaswoodguy]

That's what I do if 8lbs aren't aviable I just buy up 1-2 lbs at a time until I have 8lbs of the same powder with verying lot numbers and when my big jug runs out I mix up a new batch to avoid screwing with my charge for another 8lbs. At the hight of the last run on components most places local to me had a 1lb or 2lb maximum of any given powder per day. As MNbogboy stated mixing my own has become common practice.

 

[243winxb]

I dont blend. Had 3 - 1 lb cans. One went bad. All purchased around the same time.

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Had IMR 4198 in 2 lots. When dropped by volume, one was over 1 gr difference in weight. Measure was set for 20.5 gr . Thats a lot for a small charge.

 

[Oldschool280]

ThAnx for the replies guys, im gonna blend away.

 

[MagnumManiac]

I do it, but I will add that I only blend a small amount into a large lot.
I had a few 1lb jugs of Varget, bought an 8lb jug that sat there for some time while I used up the 1lbers. When I got to just over 1lb, I blended the lot into the 8lber. Mixed it all together and went to shooting.
I use this powder in my 22-250AI short range F-Class rig, didn't have to change a thing load wise.
I don't see a problem doing it if you verify there are no changes, I just drop back a couple of grains and re-test over the chrony and shoot for groups.

Cheers.
gun)

 

[Deleted member 46119]

ThAnx for the replies guys, im gonna blend away.

Just remember we are told by reloading guides and the manufacturers not to.

 

[Oldschool280]

Just remember we are told by reloading guides and the manufacturers not to.

Thanx

 

[Rich Coyle]

I have three seperate 1 pound bottles of mrp, i was thinking of blendingnthem
All together so i do not have to make adjustments for every bottle. Anybody doing this?

I always buy a few pounds of what I want and then mix them. That way I never run out of the one load I have worked up for that rifle.

 

[J E Custom]

There are lots of reasons people blend different lots But I wont/dont because of the inconsistencies due to poor blending.

To get a good blend you have to mix and mix and mix with no guarantee that an equal amount of each powder is present in your case. and if you mix/tumble to much you will remove the coating that helps control burn rate and damage the grains.

It is a simple process going from one batch to another with out mixing/blending. while you are loading make notes (Number the cases)of the last full case you loaded,. then number/identify the first case with the new batch of powder and test the two different powders to see if there are changes and make any adjustments if there are to the new batch to match you other load.

This way, you not only follow the manufactures recommendation, all future loads will have the same performance because the new batch has not been blended and possibly damaged.

I have bought many 8# kegs of powder to minimize the batch/lot difference and found that even then the load would change over time due to the powder degrading from opening and closing the keg. So I started opening the keg once to pore it in 1# containers and only opening them as I need them to keep the powder fresh. Another practice that the powder manufacture do not recommend is placing a desiccent pouch in with the powder because it will change the moisture content of the powder and change the burn rate. It is a good idea to place them in the storage cabinet to minimize moisture and corrosion of the container lids.

I do have some first hand experience with mixing different lots and also loading duplex loads. nothing good ever came of ether process so I stoped doing both.

This information is not intended to start a debate and most people will do what they want to. It is just my experiences of over 50 years of reloading and hopefully this advice will keep someone out of trouble.

J E CUSTOM

 

[Greyfox]

I have always avoided the temptation of mixing different lots of a powder producing velocities that were greater then the minimum ES that was acceptable to me. I worried that mixing would broaden the ES of the mixture beyond my requirements for LR shooting. I would be interested to know if anyone ever did testing to prove or disprove this.

 

[Rich Coyle]

Your statement about starting a debate is a little late. It started soon after this thread started. You just brought in something else for us to discuss: Duplex loads.


Interesting about trying duplex loads with no good results. Back in the day I made duplex loads for my .375-8 Rem Mag. I was able to get 3/8"-3/4" groups at 3,006 feet per second with Sierra 300 grainers. I discovered if I put the slow powder against the primer it worked like the slow powder and I didn't gain in velocity. When I put the fast powder against the primer I got the higher velocity.

But when Norma MRP came out I was able to duplicate that load with 100 grains of it.