I can't speak to the age of your gun, but I'd guess it's a bit older than mine, based on the serial number and the five screws. Mine is a pinned (but not recessed) 4-inch Model Ten, thin barrel, made in 1961. If I could, I'd buy a dozen of these guns and hide them away, they are far better than anything coming out of ANY factory these days. Mine has digested a shade over 65,000 +P loads since I got it, and the only damage has been a broken firing pin a few years ago. It's as tight as a new gun, and after all those rounds, all fired double-action, it's as slick as a Ferrari. Our standard warm-up drill at my club range is blasting at clay pigeons at 50 yards, and they don't last long. Mine loves Remington bullets, but also gets a steady diet of plated 158 flatpoints used on bowling pins in speed drills.
With a little TLC that gun will outlast you, your kids, and probably your grandkids. They didn't know as much about metallurgy back them, but they understood quality, and it shows!
Papajohn