Lee Perfect Powder Measure problem with WSF powder

I'm new to reloading and recently bought a Lee Perfect Powder Measure. I tried to use it to load .45 with Winchester WSF ball powder. I followed all the set-up directions including running three hoppers of powder thru the measure. I also have it mounted firmly on my bench, and I use exactly the same throw technique on every throw.

Unfortunately, I cannot get a consistent load from the measure. It might run five loads consistently, then jump as much as half a grain up or down. And over the course of 100 throws, the variation has gotten as high as 1 grain.

I also made a baffle for the hopper, but this didn't have much effect.

I'm weighing each load on a Hornady GS-1500 digital scale, and checking to make sure the scale is zeroed between every weighing.

I know that many people find the Lee Perfect Powder Measure very accurate and trustworthy, but I know that some powders meter better than others. So I'm wondering if the problem is the WSF powder.

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NRA Member. Proud to own: Kahr CM9 -- Springfield XD 45 -- Ruger 10/22 Takedown -- 1925 Mosin Nagant 91/30 -- 1944 Mosin Nagant M44 -- Kel Tec Sub 2000 (9mm) -- Western Field EMN 176 bolt-action 20 gauge

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