Based on the serial number, I'd say that this Model 28 was manufactured in 1979 or 1980.
The pinned barrel and recessed cylinder were discontinued a couple of years later, about 1982, for all models. I like these features because they were extra pains, so to speak, that S&W took in manufacturing its revolvers. They also have a certain collector appeal--or at least, some dealers think so when they write out the price tag. For practical purposes, however, they make no difference that I'm aware of. The cylinder recessing, for instance, supposedly became unnecessary with improved cartridge case strength.
BTW, I've read the opinion of one gun writer that the hole for the barrel pin weakens the frame in that area. If so, I'd guess that the weakness is more hypothetical than practical. Someone else can probably say with greater certainty, but it's not something I'd be concerned about.
Regarding the Model 28, this is a gun that I personally like very much. I have one with a 6" barrel, and it is probably the .357 that I find the most fun to shoot, with the exception of my brother's .357 SAA.
I hope this helps some.
