G'day Rod, Am I right to go mate ?
Okay then mate i'm no professor on the subject but I did learn a fair bit from some of the boys up here awhile back
I run an Ackley 22-250 as well as my 7mm and sako 22-250
When I was working out loads I was told to watch the primer and know what primer I was using ie hard-soft
Flattening isn't always high pressure signs soft will flattern more than the hard as you probably know
What I did find was a slight leakage from around the primer after being shot but on a new brass or only once or twice fired ones
with tight primer pockets the reason for new or near new brass as it's easy to get leakage around the primers if the brass is old and has slightly enlarged primer pockets especially when the pressure is reasonably high usually I got cratering around the pin indent on the primer as well if the primer
socket was a little loose
I've seen cratering caused by head spacing not being good but mine was from loose pockets
Those primers of yours look a little flat but the primers of my factory loads on the 22-250 go flatter than that unless your getting leakage past the primers or from the neck back along the shell for me it would be ok but if they got overly flat then i'd be careful and check on a few books
Blow back along the brass neck can also be caused by wrongly trimming the brass
When I got leakage past the primer i'd drop the powder back in 1gr increments til it stopped then back another 2gr that always fixed it
and that would be the max load for me
Hope this helps but it is only what I've been told , tried and tested but there would be other ways of doing things to find out high pressure signs
Hard to tell with the pic of your brass but as I said above going on the primer i'd stick with it unless problems start to appear