Lot to lot variation on Alliant PP2000MR

[spr1]

I had worked up a decent 7mm-08 load with the subject powder, from a pound I had purchased about a year ago, and recently purchased 3 more pounds. I loaded up three rounds with the new lot and the "good recipe" and today they chrono'd almost 100fps slower.
Anyone else experience this with PP2000MR?

 

[Tx_Flyboy]

What temperatures did you develop your old load?

 

[spr1]

20 degrees colder

 

[Fatelvis]

Rather than lot variation.....
Would it be possible that the year old powder was opened previously, and dried some, making it relatively lighter in weight? This could yield bigger volume-for-weight charges when throwing them,in relation to the newer, wetter, heavier powder . Just a thought....

 

[spr1]

Maybe, but I have not experienced that with other powders. It had been opened once and tightly sealed since.
I thought I recalled people making comments about newer lots running slower, so I thought I would see if anyone here had seen that.

The variation I am seeing is about .75 grains, based on the previous work up.

 

[lte82]

Maybe, but I have not experienced that with other powders. It had been opened once and tightly sealed since.
I thought I recalled people making comments about newer lots running slower, so I thought I would see if anyone here had seen that.

The variation I am seeing is about .75 grains, based on the previous work up.

What are the two different lot numbers? I have a good amount of 2000mr and I'd like to see if I have the same lots.

 

[Mad_Charlie]

Rather than lot variation.....
Would it be possible that the year old powder was opened previously, and dried some, making it relatively lighter in weight? This could yield bigger volume-for-weight charges when throwing them,in relation to the newer, wetter, heavier powder . Just a thought....

It really shouldn't make a difference, maybe if you left the lid off and out in the sun...