Although it's not a S&W, here's a short story as to why you don't want to drop a round in the chamber and let the slide run home.
Way back when, when I started carrying my Glock 21 as a duty gun at my LE job, we had an instructor that, to simulate malfunctions, did this exact thing- dropped an empty in the chamber, closed the slide, loaded up a loaded mag and handed it back to you. Since I knew better and the G21 was a personally owned gun, I argued with him till I was finally told to shut up and give him my gun if I wanted to pass qualifications. So, I did. He did his thing and gave it back to me. Performed the malfunction drill and passed qualifications with flying colors.
Went home to clean and found the bottom 2/3 chipped off the extractor hook. Gun still ran flawlessly but, when I started paying attention, ejection was inconsistent because the extractor was having trouble holding the case because it was mostly broken off. Bitched enough that the PD replaced the extractor. Should have been end of story.
The next year, this idiot did the exact same thing again. Again, I bitched, again I was told shut up if I wanted to pass qualifications. Gave him my gun, he did his thing, I did my thing and, when I cleaned at home, again I found the bottom 2/3 chipped off the extractor. Again I bitched and again the PD replaced the extractor. This time, the idiot instructor quit using his malfunction clearance drill procedure.
The way that the extractors on most autos is supposed to work is that the round is fed up from the magazine and the rim slips up under the extractor hook. The extractor is spring loaded so that it can "pinch" or hold the rim between the extractor hook and the breech face. The extractor on most autos (there are some exceptions, but nothing from S&W that I know of) IS NOT meant to snap over the rim, it is meant to open up a little when the rim comes up from below. Try to snap the extractor over the rim and you risk chipping or bending the extractor hook to the point that it won't hold on the rim. Use the proper procedure; load the mag, chamber a round from the mag, then remove the mag and top it off.
Bub75