S&W fixed sight guns had front sights that were integral to the barrel forging. Since stainless steel is pretty well the norm anymore, and silver sights are near useless, it is pretty well the case that front sights are pinned now.
Adjustable sight guns have always had front sights that are pinned, and this includes all Model 27s. Some guns had ramps that were integal and the blade only pinned to the ramp. Some had the sight blade and ramp integral and the ramp was pinned to the barrel. If you look very closely on both sides of the front sight ramp you will see a small circle under the middle of the blade which doesn't quite match the color of the ramp. this is the pin. The pin is .055", less than 1/16". If your gun dates back to the 1950s the ramp is pinned, you won't be able to replace that one.
There are two widths of front sight tenons. One is ca. 1/16" and the other is 1/8". The thinner one is old too. If your gun is a 27-2 or later the sight has the 1/8" tenon. If you want to replace this measure the height of the sight blade above the ramp top, this is how they are measured. But the correct height blade and take the gun to someone who is familiar with doing this work. While simple in practice this is a job easily screwed up, badly.
And the word is patridge, a man's name, it was not named after a bird, the partridge. And, a gun has sights, something which is seen. Site refers to a location, such as a construction site or web site.
