Be a bit awkward testing the AA cylinders after 10 years, or any time period.

They deform if overfilled and would not take the test pressure. What other manufacturers test to I don't know. If all cylinders are tested (not just samples) I can't recall seeing any stampings for any manufacturer. Some cylinders do have it etched on but would that be good enough ?

Do the "Bottle" rifles have tested/stamped bottles ?

ATB
Ray