I suspect the truth is that ALL primers vary somewhat in diameter, depending on the lot, due to the wear-use of the cup-forming dies.
John, that's exactly what I've seen.
Even primers that seem loose don't leak around the circumference due to the cup expanding when the primer goes off. For those wanting to work with primers, uniforming the pockets with a non-adjustable carbide uniformer takes care of 90% of business by standardizing the depth and removing the chamfer around the bottom of the primer pocket. Then, using the uniformer to clean the primer pockets keeps the depth constant.
How much, if any, material comes out of the pocket during load work is a pretty good indicator of things, too.
Good shootin'
-Al
