The date on the NEMA page is perfect.
I raised the issue a few years back to a meter-socket manufacturing engineer [if here's any place that nipple/raceway lineup is not easy] and he mentioned that keeping sets of one-pass concentric punches and dies sharp is a pain and costs a lot of money for a yearâ€™s worth of stamping.
He seemed nice on the phone and followed up with a letter offering to quote â€˜less knockouts and hub openingsâ€™ on quantities of 100+ sockets, provided, of course, no UL labeling was needed. (!) He balked at asking for three.
The same outfit did keep a good inventory of NOKO versions of cans and gutters, and I took advantage of that perk.