your right fella, you can buy rated eye protection for around a fiver, most cover you to EN166-F1, fine for low force impact... which 500fps is not.
Pay a little more, and go for the proper safety standards, ANSI, quoted from the Oakley website as they lay it down in simple terms
"For the high-mass impact test of ANSI Z87.1, a 5-inch metal spike (17.6 ounces – more than a pound of weight) is dropped on the lens from a height of more than four feet."
Now facing 500fps seems a little less daunting, would I buy copies? no, plinking, i'd prob use the screwfix goggles, skirmishing, esp