I just went on Gunbroker to examine as many M442s as I could find that showed a view of 'the gap'. All the ones I saw (even no-dash versions) had some amount of gap, although none were as bad as your first example nor any as good as your second one.
I recently purchased an L frame and an N frame, both new, online. Neither one showed a significant gap, although both had other issues that had them back at the factory for correction.
I think that S&W have probably loosened some tolerances to cut costs, and those loosened tolerances permit visible gaps like the one you are discussing. They have had several bouts of varying quality over the years. Recall the Bangor Punta era.