Just got a set of 302s (and a set of 551s) and the 7-iron doesn't have the serial number on the hosel. Got them from Japan and so was thinking I don't need to worry about authenticity. Do Epon irons always feature the serial no on the hosel of the 7-iron?

That was my understanding.

Yes, the older irons are more etched surface and can fade slightly, the new ones are deep engrave.

Buy, try and sell about 5 sets of Epon irons. All of them have it.

Got it! Had to look closer but yes, they have the etching. The 551s had the deep engraving. Thanks guys!