Rox --- that is the same story I have heard on 210 and 210M.
Any more info??
The only quantitative comparison I've seen is this one:
www.castingstuff.com/primer_testing_reference.htm
It's a rather small sample, but it does back-up the idea that they are generally the same, but with a marginal improvement in consistency in the 'M' that may only be significant to statisticians or shooter psychology.
You may find more data on comparative velocity stats if you search.
Whether the operator story is true, or ever was, I have no idea. It could equally be that the batches that perform better during testing are given the 'M' designation, and this has been suggested in forums alongside the other story.
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