I bought a 2016 4" 586-8 .357 magnum revolver last year from a guy in Laramie. It came with the box and all the factory goodies and paperwork.
He's more of a collector than a shooter and said that he had two of them and had only put about 50 rounds through this one and was selling it to get a new Performance Center model 29.
Took it home and cleaned it then went to the indoor range with 50 rounds of Federal American Eagle and 50 rounds of my 38spl reloads and was getting light strikes with both the Federal and reload ammo. Not every shot but about 2 out of every 10 rounds. Took it apart to inspect everything including the firing pin and didn't find anything wrong.
Put it back together and was getting the same thing so I suspected a too short firing pin but couldn't find a spec for it so ordered a longer pin from TK Customs.
After installing the longer firing pin was still getting light strikes but fewer so took it apart again and noticed a rub mark on top of the firing pin which indicated that it was touching and being deflected by the bushing as it moved forward so I took a stainless steel drill bit that was .010" larger than the pin and slowly ran it through the bushing using a tap holder instead of a drill.
Carefully cleaned everything, reassembled it, took it out to the range again and Shazam!, no more light strikes with either firing pin installed.

Attached Images

S&W 586-8 A.JPG (79.8 KB, 36 views)

Got it working correctly and saved all the aggravation of a trip back to S&W!! That's all that matters. Good job.

Thanks. I try to fix things myself and after 50+ working as an industrial and motorcycle tech have the knowledge, skills, and tools to handle a lot of things.
Plus the smarts to know when to have someone else take care of a problem.
Wood for instance. I can bend nails, make sawdust, chips, and splinters but that's about it.