I think I can give you some input on this, as I'm a certified Glock Armorer and also specialize in Glock trigger enhancements as well as custom stippling. If you google (or facebook) Tactical Texture and Triggers, LLC. That is me...
Anyway, the vast majority of stock Glocks have a trigger that is much rougher and heavier than it needs to be, and changing out a simple piece like a spring or connector is not going to cure the problem. The internal parts are typical mass-produced quality, with very rough surfaces that need to be more than just polished - they need to be trued up first, otherwise all you have is shiny rough metal. If you really want a great Glock trigger, you're options are to either
A. Get the gun to someone in your area (or ship it to a qualified FFL/Glocksmith) in another area, or
B. Buy a drop in trigger system for it, which is NOT an option for the 42 at this time.
Either of these two will make the Glock feel night and day different in terms of trigger feel AND you will still have a gun that will eat any ammo and require less than normal maintenance to keep you and your family safe.
Now onto the bad news: The 42 is NOT a typical Glock. The internals, ESPECIALLY the trigger system is VERY different than ANY other Glock. In fact, there is only ONE piece (firing pin safety spring) that will work between the two. EVERY other piece (trigger bar, firing pin safety, connector, etc.) is SPECIFIC to the 42 ONLY!
As far as a Glock goes, the stock 42 has the worst/heaviest trigger of the bunch, but it can be made
much better. The Glock 42 was only released at the Shot show in January of this year, so there are really no aftermarket trigger parts to swap out. In fact, there are only a few places that make sights for it, and you need a special tool I just bought to adapt a traditional sized sight pusher to hold the super small slide.
Now don't get me wrong, the 42 is a great gun, and I got one for my wife for our anniversary (see picture), it's just that it's a very different Glock, and there is less that I, or any other skilled smith can do to make it better, at least right now. I have made hers dramatically better, and a stock trigger will get noticeably better the more rounds you put through it, but a every other Gen 3 or 4 Glock trigger will start out WAY ahead of this little gun and stay there.
*NOTE: This Glock 42 has my texturing (stippling), trigger work, and the Pearce Mag extensions. The gun also has a new set of XS Big Dot sights for the 42. My wife LOVES this little gun!!!
Mike...