My Chargemaster 1500 RCBS easily measures to within .1 gr.
Even when using the automatic dispenser (which you can buy separately), it consistently drops and weighs charges, automatically at the push of a button, that are on the money with an occasional .1 gr. variation in the powder charge (not the scales' ability to measure it). That's loading rifle with IMR 4064 extruded powder.
When measuring pistol charges if there's a .1 gr. difference, it's probably because the powder measure on the loader is set right where the .1 gr. reading changes to the next higher or lower. If I week the powder measure adjustment on the Dillon and all charges once again measure to the same .1.
If you want .01 accuracy, then weight ten powder charges all at once and get the average. Or just 5. You might find that 5.5 on the scale really averages 5.55. right between 5.5 and 5.6 grs. Personally, I've quit worrying about those silly little variations since they wouldn't affect even fast burning pistol powders. Not much on the chronograph, either.
My older model RCBS also was accurate with no .1 gr. variations when using the exact same known weight to test it.
Just make sure you zero the scale each time.
NEVER leave any weight on the scale. On or off. Especially over a period of time when not in use. That will ruing a scale long before leaving it on constantly would. In fact I used to leave my original RCBS scale on all the time. It wasn't until I forgot and left it on with weight on the scale that it quit on me. I'd had that scale for over ten years.
Bought a fancy Lyman scale that wouldn't calibrate. Took it back to Sportsman's Warehouse and exchanged it for the RCBS 1500 with auto dispenser.
Never looked back. You can store your favorite powder charges in the memory. Great for rifle reloading on the single stage press.
Push button, powder dispenses into pan, use funnel to pour in case. Set pan back on scale. Push button. Seat bullet. The next charge will be waiting in the pan where you can read the charge. Repeat process. You'll find that the machine will keep up with you---if you can keep up with the machine.
If you're fussy about the occasional .1 gr. different when you're loading 50 gr. rifle loads, trickle in to exact amount.
Note: Electronic scales measures to a tenth of a grain, then at a certain point kick up to the next higher tenth (or down to the next lower). I have a pan that seems to be right in between two points, so I can get the .1 variation with no weight on the pan--even after zeroing. I use a different pan, I lose the variation.
Moisture has been mentioned as something that can effect the charge. True, but not the scales ability to measure the consistency of the charge--with or without the moisture.
I still recommend the balance beam scale for back up and variation.
