Thanks very much for that, JimmyD.
It's good to see that the RCM has that type at 20 grams, because KM has it lower (16.45 grams), but several folks have measured the 1973 proof at 20 grams. https://en.numista.com/forum/topic160622.html
My guess is that wherever the 1974 was struck, it was struck with a slightly lighter planchet, and it's a screw up in the KM catalog.
It's good to see that the RCM has that type at 20 grams, because KM has it lower (16.45 grams), but several folks have measured the 1973 proof at 20 grams. https://en.numista.com/forum/topic160622.html
My guess is that wherever the 1974 was struck, it was struck with a slightly lighter planchet, and it's a screw up in the KM catalog.


















