hyrax wrote::agree: A good scale like this one (with the calibration weights) will serve you very well. A bit more upfront, but in this area, you really get what you pay for.
If you're spending $120+ on a digital scale, you might as well shell out a bit more for one of the auto-dispense versions. But, NOT the RCBS Chargemaster. It is known for having circuit boards and touch pads burn out frequently. (With the limited warranty on RCBS's electronic devices, it's a poor choice, even if you plan for it fail.)
If you just need an accurate, dependable scale, the RCBS 5-0-5
is the scale all others are judged against. It's not the cheapest. It's not the most expensive. It's just a good, accurate, dependable, average scale, for the average reloader. As a bonus, it's one of the easiest to set, adjust, and read.
I am not a fan of digital scales, unless they were specifically designed for reloading. I have used everything, from cheap Cabela's scales, to $5k digital laboratory scales. Unless the scale was specifically designed for powder handling, nearly all digital scales will "drift", as you trickle a powder charge. In one extreme case, I was able to get a $90 Cabela's digital (that they CLAIMED was a reloading scale) to drift more than the total weight of the initial powder charge. I was trying to trickle up from 3.9 grains to 4.6 grains. By the time the scale read "4.6 gr", there was actually 10.1 grains of powder in the pan (verified on my balance beam). Nearly 6 grains of drift! I later tried the same test with a rifle charge, to see how things compared in different areas of the range's capabilities. With a 48 grain powder charge desired (trickling up from approx 44), I had 62 grains in the pan, before it showed the desired reading. I believe this comes down to a really simple explanation, if you're electronically minded, but would probably be really confusing, if not. Either way, I still haven't found a digital scale I can trust for powder handling, other than those sold by reloading companies (NOT Cabela's).
If you don't understand electronics, skip this sections.
I think the issue with these scales, comes down to improper data handling with a comparator. Let's say you have a 10 grain powder charge sitting on your scale. Display memory is holding a value of 10.0 and a corresponding value from the load cell. When a few granules of powder are trickled in, the scale senses a change. The scale calls up the load cell value from Display memory, compares it to the current value, and passes the difference on, to be compared to the threshhold for increasing the display value. The threshhold value is higher than the difference between the other values, so the scale does not increase the display value. ...And then it does something bad. Instead of leaving the existing values in Display memory, it writes the new load cell value. So, it now has the same 10.0 gr value for the display, but associates that with the increased load cell value. When this process is repeated several times, you end up with an actual charge weight of 10.2 or 10.3 gr, but a displayed value of 10.0, still! Repeated further (especially with really slow trickling), you get massive discrepancies between displayed weight, and actual weight. Again, it's just my theory, but it makes sense for scales that were not designed to handle powder trickling.
I need a new signature. This one sucks.