Dave, I apologize for not recognizing this when you first posted.
Here’s a scan of a page from R. L. Wilson’s WIINCHESTER, An American Legend.
“The Model 59, Winchester’s next semiautomatic shotgun, reached a total run of over 82,000, from 1959 to 1965. At top, the rare experimental 14-gauge, with aluminum shells and a box of cartridges. Only about twenty-eight were made.”
From the text; “Just over 82,000 were made, and among that number was a novel 14-gauge experimental group. These were tested at Nilo (Olin spelled backward) Farms, the factory’s exclusive field-test facility, and although they performed admirably, the concept was dropped. Winchester officials thought that educating the public for the new cartridge would prove an insurmountable task. The cartridge had an aluminum case and was of a special short length.”
Note this box shows #9 shot and yours #8.