Re: Hornady LNL AP metering
I had the same problem. Frustrating.
In my case, I've found that much of the problem has to do with the fact that my reloading bench it's mounted to has a bit too much "give"...
Put another way, when FL sizing a case, especially if I hit a stubborn one, running the ram will really vibrate/shake the powder drop- sometimes pretty heavily.
This is BIG no-no with the extruded powders. It'll cause the already metered charge to compress, and allow more powder into the meter.
Just try this- drop and weigh a charge (any weight) when the powder drop has been vibration/movement free. Then, give the powder drop a few good shakes, drop the "same" charge, and weigh it. It'll be from a couple of tenths, to as much as five or six tenths more.
I've eliminated much of my Varget metering misery by really stiffening up my benchtop, and the rigidity of the AP mounting to minimize vibration/movement during loading.
Don't know if this is part of your issue, it was mine. Varget will never be as dead on as a ball powder, but I'm almost always within .2 now.