Size you need
I too have a 696. I emailed S&W back in 2007 about getting a replacement front sight with a gold bead. This is the reply I got from them:
----
Hi,
Front sight on your gun is a .278 red ramp. It is a pinned front sight.
We do not offer a front sight as a part sale in this height. The gun would have to be returned to have a front sight installed with a gold bead. Cost would be roughly $70.00. Please see attached
Thank you
kf
-------
and they attached a work order I could use. I don't know if things have changed, but at least you know the exact height of the stock unit!