All the common RCBS scales use exactly the same knife edge/floating agate bearing set-up so none is more accurate than the other. The 502 is a simple two poise scale, the 505 a three poise scale, not necessarily better, some prefer it for easier setting but it adds something else where errors can creep in. The 5-10 and 10/10 use exactly the same beam with a rotary poise system. All these scale are now discontinued, they were dropped by RCBS around 4 years ago. They have been replaced by two new beam scales, the M500 and M1000.


All RCBS scale (made by Ohaus) produced for the last 8-9 years were either made in Mexico or China with variable quality.


A Redding No 2 is usually a good bet.