Federals have always been a snug fit, but the latest two bricks of Fed 210M primers I bought are IMO a too tight fit in the primer pockets. They take a lot of force to start, and when they finally do go some of them go in in such a way to make me wonder if I've crushed them.
The unplated WLR's have been a bit of a loose fit in some brass for a while now.
The R 9 1/2 primers go in smooth but snug enough, but they run tall. Combine that with the off spec primer pockets commonly encountered and they may not seat flush.
Overall the CCI primers have been the best seating ones for a while.
(All comments refer to large rifle primers.)
