Can't agree with you there - The M5 is an excellent scale and is the forerunner of the 10/10. The M5 and the RCBS 304, also made by Ohaus were about the peak of beam scale quality. From that time the scales have steadily deteriated, quality being dictated by accountants not engineers.
I picked up a vintage M5 and couldn't be happier. With larger grain powders, it's already "single grain" resolution. Honestly it's as precise as anything I need now because it can deliver an error of about 0.1%, which is good enough to make charge weight less variable than most other things.
I'm not sure why you'd want to "check" at 260.9gr when most of the time we are weighing much lighter charges. The range of 20-50gr is where I really care about being closer to the true value. And of course, resolution and precision-- not accuracy per se-- are what we care about. It doesn't matter if the scale says 33.8gr when it's really 33.76492gr. What matters is 1) that the same weight always reads the same, and 2) the scale will move to reflect tiny changes in weight-- well under 0.05gr.
That's the same scale as the Superb Ohaus 10-10 Scale that's been dumbed down by not including the revolving tenth-grain barrel and painted an uglier color. It's been available for over 50 years ! . If you sent it direct to Ohaus, they would've "Fixed" for Free ! .
