I've had good luck with 5 Star Firearms brand speed loaders working with the newer factory S&W boot and aftermarket grips. Most speed loaders would work when Uncle Mike's provided their boot grips to S&W but when S&W switched from Uncle Mike's many speed loaders no longer worked.
Recently bought four, 2 Model 442s and 2 Model 642s. All were built in the last six months and seem to be close to perfect. Just lucked out I guess although I always give them a good looking over.
I believe 1982 was when S&W decided to stop the pinned barrels but I also think it was a year or so before they ran out of the parts on hand at the factory.
442 (Model 178034) from the Performance Center with factory action work. Easy to carry in an ankle holster with excellent trigger and mechanics. Folks at the range always ask about it since they mainly see "black" semiautos.