What exactly makes a cartridge obsolete? Are game animals any tougher now? Do bullets suddenly bounce off them?
When ammo manufacturers stop cataloging a cartridge it becomes a handloaders only proposition and if there isn't any factory ammo being cataloged soon there probably won't be any factory rifles cataloged either. Companies are good at introducing new cartridges, but not very good at supporting them if they lose market traction/share.
Think of all of the cartridges that have been all but abandoned by ammo manufacturers over the past 50 years, including the ones on this list:
5mm REM MAG, 22 WRF/REM SPL, 222 REM MAG, 223 WSSM, 225 WIN, 243 WSSM, 256 WIN MAG, 25 WSSM, 260 REM, 6.5 REM MAG, 264 WIN MAG, 270 WSM, 7-30 WATERS, 284 WIN, 7MM SAUM, 7MM WSM, 280 REM, 300 SAUM, 300 WSM, 307 WIN, 8MM REM MAG, 356 WIN, 375 WIN, ETC.
Most shooters aren't handloaders, so the market for the most common cartridges get the manufacturing priority, leaving a lot of good, useful, but old cartridges to be produced as "seasonal" or "occasional" runs, so that ammo isn't always available and in recent years old standards like the 30 REM, 30-40 KRAG, 303 BRITISH, 32 WIN SPL, and 32 REM are scarce in many areas. Scarcity leads to hording and hording leads to more scarcity, not a positive thing for the one box of ammo per year or so hunter who generally isn't one to plan ahead.
