Does anyone have 1976 SSPC cards that are definitely genuine--or know how to tell?

[butchie_t]

I sampled 8 different cards from each set that I own and measured them.

The 'regular' set averaged 2.49.. x 3.49.. in height and width.
The 'error' set had the exact same results.
The thickness was .65 mm on every card I measured for thickness on both sets.

I still need to weigh them and will update this post with those results shortly.

Height, width, and thickness were basically the same between the two different sets. Picture cropping was consistent between the two sets as well. I did not see any real significant differences between the two sets. Nothing that jumped out at me anyway.

So, whoever printed the 'error' set had a good knowledge of what the regular set was printed and cut on. Speaking about the cuts, both sets look to be cut the same between the two sets.

All of this above are strictly my assumptions based on what I measured between the both sets. Purely speculative on my part and nothing more. But it does tend to shed some light on the two different sets and how well they mirror each other.

Sure seems like a whole lot of work to generate a number of supposed error sets years after the original printing had come and gone years before. IMHO

Butch Turner