I just bought a S&W 629 with a four inch barrel. These have been unobtanium around here. In fact, I do not remember seeing one in the last five years. After getting it home and reading up on it, I notice that at least some current 629's have the two piece barrel. This one does not. If mine does, they sure hide it well. Also, I noticed the gun is so dirty I find it hard to read the SN. Maybe the store clerks had a little shooting session last weekend. I am okay with that, but I am beginning to wonder if this gun is actually new. SN is DZF****, and the model number is 629-6.
I just looked at my 6 inch 629 with underlug. It is a 628-8, and does not have the two piece barrel either. Finish is the same. It is a shooting fool with the red dot, but a little heavy for a perfect packing pistol.
I seem to remember that a different dash number does not mean a later gun, but a different variation. In other words, maybe the underlugs were dash 8's and the regular barrels are - dash 6's?