Mine is from 1972.
I don't know about "powdered metal".
I do know mine is a well balanced, well pointing, great shooting .357 magnum. The trigger does stack but it is smooth. DA is fairly heavy, but not ridiculous. The SA is very nice.
The workmanship on it is flawless. The bluing is extremely well done in deep blue/black. There are no tool marks anywhere on it, and the wood grips have sharp checkering with bright silver Colt medallions.
FYI, mine was $400 out the door, in a well worn box, but the gun was mint with a hint of a cylinder line. I figured any gun this nice from 30 years ago would be worth it.
Cylinder and Slide offers a couple of packages for these guns. A duty job, and a target job.
Although if I swap the springs for lighter ones, I wouldn't see the need for anything else to be done to it.
I'd probably snag another one if the opportunity presented itself.
ANIB older revolvers are always a good find.