I was wondering if
anyone might know if the old A17 series (S and ST) solid rivets had a
more domed head on them than the current AN470/MS20470 series do?

As someone else posted S and ST stand for the type of alloy the rivet is made
of. However raised head rivets prior to the AN470/MS20470 Universal Head style
were of three types.

There was a Flat Head style where the raised head was actually flat looking
like the head of a clevis pin. There was a Round Head style where the profile
of the head was higher and of a smaller radius than the Universal Head. And
there was a Brazier Head where the profile of the head was lower and of a
greater radius than the Universal Head. Don't have any references with me but
all had AN numbers. I am not sure if the overall diameter of these heads
varied in size but each required a different rivet set or snap to drive.

The Universal Head was developed specifically to replace all three of the
previous raised head designs and thus lower tooling and parts costs.

John Dupre'