Will a replacement complete slide fit my pistol without having to do any special fitting or must it go to S&W or a gunsmith?

99 times out of 100 it will be no problem.
The other 1 percent of the time it will be a misfit at the barrel hood to breech interface or even more rarely, the rails will be too tight (a stack-up of production tolerances).
On TDA models (DA/SA) with worn rails, decock timing could be an issue, but that seems to be more of a problem for alloy framed pistols.

As the model to which you are referring is an all stainless steel DAO model, that would not apply to you.

John

DON'T FORGET THERE ARE 2 DIFFERENT DAO SLIDES FOR THE 5946. ONE IS A LITTLE LONGER THAN THE OTHER. JP

What th'? Never heard that before. Could the longer slide be on the 5946TSW? The SCSW doesn't mention that.

Thanks for the comments.

Within the standard models and early, non-railed versions of the TSW models, DAO slides are longer than TDA (DA/SA) slides.

Within the later, railed TSW models, slides are the same length whether they are DAO or TDA.

John

Good info. Thanks.