I don't know what the pressure was in these rounds, but when I slide my fingernail across the junction of the case head and the primer I can barely feel the seam.

Do you have any USPSA clubs there or near by? Major 9 has become quite popular with Open shooters being as the brass is so much cheaper than 38 Super or 38 Super Comp. 9mm loaded long and real hot to make major power factor. They get once fired brass, generally use it only once themselves and then don't bother to pick it up. If you shoot at a range that holds USPSA matches you'll find it, and you'll know yo found it when you go to seat a primer and you'll think by feel that there wasn't one.

Mike Dillon wrote of ruining a bunch of .45 ACP brass buy tumbling it in the clothes dryer. made all the mouths of the cases too thick or some such. he ruined several cases and wasted lots of time with it. He scattered them at the range were he shot IPSC...dirty trick....

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Of the Troops & For the Troops

CAS pretty well sums it up. Its foolish to pick up range brass, you get more grief than cost savings regardless of who has been using the range. I tried it a bit 50 years ago.