S&W 442
The 442 I carry has held up quite well. It is the model with the lock. FYI, I asked a S&W rep about the finish on the cylinder, and was told (as I suspected) that the cylinder was not blued, but had the same "ion bond" ( I may have the name a bit off) finish used on the 340 M&P. Looking at my 442, I suspect the barrel likewise is not blued (i.e., black oxide) but has the same finish as the cylinder. I understand this is a very durable finish. I like my 442 a lot.
Judging from the used guns I have seen, I think that the dark finish of the 442 my actually be more durable than the 642 frame's finish. Others my disagree. I agree that any wear on the dark finish would show up to a greater degree.