John,
We had 140g Berger Hybrids running sub 2 inch groups at 500 yards.At about 50 55 degrees.
Its a very clean powder.
Meters great.
As the temps climbed over the course of the day our accuracy went out the window.
Im thinking its the amount of change in temps.
If your looking at a 20 degree temp change over the course of a match.Im not sure how you can use the stuff.
Your claimimg problems at zero temps.
I think they need to get back to the lab with the stuff and try again.
I dont mind trying stuff and putting time in to figure stuff out.But i've seen enough.

dave

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Only accurate rifles are interesting.