S&W will repair your rifle at no cost to you. No shipping charges. No repair problems. There's no preventive maintenance program I'm aware of. Have a problem? They'll take it back. They can't fix things that ain't broken.
Mine went thru just over 300 rounds with only a few failures to feed, then experienced an out of battery discharge. This was back in December. DTM-serial.
Rifle was updated to whatever "latest spec" was vogue then and returned in less than two weeks. Has over 1000 trouble free rounds since then. Functioning has been too good to even comment after every range session -- the lil carbine has become positively boring. And positively accurate chasing shot shells around the range.
I did the "15 Minute AR15 Trigger Job" on the rifle. Cut off the right leg of the hammer spring, reformed the trigger spring. 100% reliable ignition.
I also polished the feed ramp and aggressively polished the chamber. Anything that prevents complete chambering of a .22LR round will result in an OOB discharge because the extractor holds the cartridge against the bolt face.
Oh, yeah, I'm shooting Winchester 333 bulk.
-- Chuck