I don't know nothing about no bevels!
It could be the photos, but the cylinders look the same to me on all three guns (except for a darker blue on the 17-2). All have the sharp corners at the front of the cylinder flutes knocked off, but it varies a little even from flute to flute.
I suspect the biggest cylinder change was reversing the ejector rod threads around 1959.
There's a lot of speculation on my part , so don't take it too seriously. It makes sense to me, but crazy people think they make sense too! [img]http://www****nemasterstudios.com/graemlins/images/spin.gif[/img]