Re: Question for Dave D
A simple solution would be for the person who writes the weight in grams to add another # or code indicating a born-on date...this would be easier than changing the hotstamp as per Millenium's method.
A, B, C, D for each of the 4 seasons (Winter through Fall) accompanied by the year...ie D/3 for Fall/Autumn of 2003, for instance...
The code, just like the weight would wear off with use, but who really cares at that point. An unthrown or newer disc is where this would matter most to the collector/thrower.