No disrespect intended toward your gunsmith, but it's *possible* that his reamer was worn, just as S&W's reamers wear as cylinders are manufactured, eventually resulting in undersize cylinder chambers before they change their tooling. If that was the case, he may not have removed enough material to bring your chambers into SAAMI spec.
Please post the results of your own reaming when you receive your new reamer. I'm curious whether you'll remove much material since your gunsmith already worked on your chambers.
Some of the .22's I've done have taken quite a bit of work to bring into spec (lots of turns, lots of material removed) and some took hardly any time at all (very few turns, very little material removed). The good news is that all my .22 revolvers will now shoot ANY ammo I've run through them with absolutely zero extraction issues. This includes a bunch of S&W's, Rossi, Taurus, and Ruger revolvers.
Best of luck in your endeavor!
Lou