I have two of the Lee's and one works consistently better than the other, so you might try returning your's to Lee to see if they find something they can fix?
That said, if stick powder is what you are throwing, the single best measure I've tried that, for me, is consistent within 0.2 grains every time, is the JDS Quick Measure
. It's design completely prevents grain cutting. It's a little less convenient to set up initially, but the removable charge tubes let you keep separate ones for each charge weight you use frequently if you want to skip the setup. Tubes are available large and small. It's my go-to stick powder measure. There's a review here
, in which the person doing the comparing didn't get results as good as I do, but which still finds it beats the popular Redding 3-BR. I'm not sure why I'm getting better results than the reviewer did, but so does writer Rocky Raab, so I'm not alone.
For spherical propellants I've had good service from the Redding drum measures. I use the BR-30, but it won't get you to magnum single-throws, so the 3-BR might be your option there. Other's drum measures probably do pretty close to equally well. It's hard to throw sphericals really wrong as long as the measure doesn't leak.