I have used a pocket primer swager that I had purchased from Midway several years ago. Primers sizes and pocket primers can have variation and this tool works great with no effect on accuracy. The pockets will hold for several firings. I have found both Remington and Federal match cases to have loose pockets. Now, as was the case during the last shortage of components when I bought mine, this is a useful tool. It should not be used if the cause of loose primer pocked are the result of too hot a load being used.
"Let us speak courteously, deal fairly, and keep ourselves armed and ready"-T. Roosevelt
I use Lapua brass exclusively in my competition rifles, and in time, those pockets expand too; with no other pressure signs, especially in the 6 Dasher. I have found that Wolf primers are slightly larger, and will fit snug in pockets that have expanded. Some people say the Hart tool is OK, but you need to use it with each loading.
If you have no other pressure signs, it is soft brass. Barely loose I would run a few more loads thru em. If the primers fall out, toss them.
I wouldnt nessisarily be bad mouthing fed brass. The wsm is loaded to real high pressure. As high as the weatherbys and at that level about all your going to get out of any case is 3 or 4 loadings. back off a couple grains and youll go slower but your brass will about double in life.
"...I have reloaded Federal brass in 243, FL sizing, up to 8 times with mostly non-max charges level that results in medium velocity yet flattened primers (no other pressure signs) and yes some primer pockets are getting very easy. I've recently had a few cases that started to rupture horizontally about 1/2" up from the case head. But this is after 8+ reloads."
Flat primers and incipent head seperations are effects of exccesive effective headspace caused by too much shoulder set back in FL resizing, not excessive pressure as such. "Flat" primers really don't tell anyone much about presure but expanding primer pockets sure do. 'Saving' significantly over-loaded cases with stretched pockets by using a pocket reforming tool doesn't appeal to me.
Federal cases are great for long life with normal pressures because it is a bit soft and therefore can withstand the effects of more reloading cycles before it work hardens enough to split but Fed can't take excessive pressure as long as harder cases can. I like long life and feel no need to push the pressure limits so Fereral cases work great for me. You decide what you prefer and live with the downside.
I doubt anyone thinks the OP is still checking here, these new responses are aimed at current drop-in reloaders having the same problem.