As a note on "Flowing primers"............
2 of your 4 in the picture, had "wiggle room".

I just did a test with two medium slow powders in a 5" 9mm with a 124 Jhp.
"X" with 6.0 grs did 1222fps
"y" with 6.1 grs did 1233fps.

The 1222fps cases had flattened, 100% primer hole fill up..........
the 1233fps cases had 50% of the cases with "Wiggle room" to spare.

Plus the primers used were soft federal's and not my normal cci small pistol primers.

I agree on the use of a chrony to help with load pressures but a flat surface primer
is a good sign that you are in the full load area.