Just a few things to add:
1) Some wheel guns (per manufacturer) are just fine to dry fire... Ruger revolvers come to mind. Since I am a Ruger fan, I contacted them for verification of this. They said: "Its not only fine, it will improve the trigger".
2) Using spent brass with a speed-loader sucks, as it needs re-sized to fit quickly, and STILL does not have a nice round/conical nose to guide the round into the cylinder (like the faux bullet note of a snap cap). IF you put bullets in these "empty" cases, they would look too real to be safe, and would still need something to absorb the firing pin energy of your "flimsy S&W" :lol: Unless you have one of those "brick outhouse" Bill Ruger products!!! (Easy folks I'm just kidding.. I have a S&W that I'll not be getting rid of any time soon).
3) By the time you make 10-12 "faux" cartridges, you will wish you had spent the $10-20, as the inserts I made back then were a PITA!
On a personal note: I made some "dummies" as a youngster (I was 11) for an old 1894 Winchester "30 WCF" lever-gun, as I was told not to "dry-fire" it, and was too cheap to buy them... In disobedience of the household gun rules, I did it anyway, and while breaking numerous other family and boy-scout gun rules, proceeded to confuse the dummies with live ammo (yes part of why these were truly "dummy" rounds was that I stored them with live ammo
). Standing in the living room, I was aiming at a bird feeder in the yard (we had 25 acres bordering PA game land), and blew a 5' x 6' picture window out of the frame, and ruined a handmade bird feeder. My parents were very strict, and I deserved all the punishmint/restrictions/labour/restitution etc that was due such a grossly irresponsible act. I am; as a result of that one event, a safety nut that winces visably at the suggestion of "home made" dummy rounds. Snap caps are not cheap, but that was a $800 window in 1989! I delivered 3200 phone books on foot/bicycle to pay for that window!
Fabricator