I got a chance to try the correct loading procedure with great results: every brand functioned flawlessly! It may be worth mentioning to this surge of new owners of rimfire rifles with hi-cap magazines. It requires a little more attention to loading as compared to the conventional 10-round mag that typically does not have or require the load-assist lever. DO NOT use the lever until necessary, and then only just enough so as to "assist" the other hand in inserting the round. Be sure allow each round to be properly aligned (with the cartridge rim on top in front of the one below it). Be careful to not pull the lever too far and let the round fall into the magazine.
I got mine 2 weeks ago. I used Federal, Winchester, CCI and Remington, each with the same result. I have only fired 300 rounds through it so far and have experienced about 16 Failure To Feeds, just over one in each magazine. A round would get turned perpendicular as it travelled out of the mag and then get rammed in the side by the bolt causing a jam. I have had zero FTE's, had a few miss fires on the cheap Remington stuff, but I have never heard anything good about this kind of ammo anyway. I contacted S&W about the problem and they said specifically to NOT use the magazine assist lever when loading and to physically load each round unassisted and try again. I will report back as soon as it quits raining here. Other than that, I love this new gun!