A good example of a mix up like Gordon was eluding to is a
Mosler I mounted incorrectly.
Most modern locks are now adapted to be mounted VU, VD, RH, or LH. However, this particular
one happend to be a strictly left-handed lock. So when I mounted it RH it caused the drop-in area
to be at around 50 (180 degrees from where it should be for a Mosler.... zero). Yes, you could still
put a combo in, and yes it would still function properly. But your drop-in/contact area/forbidden zone
would not be true to the manufacturer and would also limit the use of some of the mid-range numbers.
The contact area (drop-in area) differs slightly with each brand. Your S&G should be around 5-15
The other thing to keep in mind is the
orientation of the spline keys' flag. Some locks call for the flag to
rest over the spindle, while other locks require it to point away from the spindle and rest over the cam.
I've messed
this up before too, lol, then realized the spline key was grinding against the cover plate :/