What scale should I be looking at today since the Lyman M5 is no longer in production?
I would be looking for an old M5 in tidy condition or an old Redding No 2. Nothing offered new in the last 10 years will be better and many of the new scales leave a lot to be desired.
Also worth considering would be an old RCBS 502, the old RCBS 10/10 or 5-10's although good scales can develop a bit of slop in the barrel poise if well used.