There is no exact science to reading primers. If you
really want to come to some conclusion by reading a primer, I would suggest that the only way you can reasonably do it is to build a bunch of loads that are
exactly the same (except for varying powder charge) and shoot them all from the exact same platform and only
then try to make some sense from reading the primer and how it looks. Same brass, same bullet, same COAL, same pistol.
And make sure your primers are all the same brand and from the same lot.
I've seen light loads make primers look "heavy" and the opposite also. There's a lot going on in there and glancing at a primer doesn't tell you much.
As for the recoil spring... I put a 22-lb Wolff spring in my 1006, also circa 1992. And I did it on the recommendation of on Mr.
The_Shadow.
It was good advice when he gave it to me more than three years ago back in 2008, and it's still good advice now. Not only is my 1006 easier to field strip and put back together, my brass doesn't launch in to the next county.
I believe replacing a 20-year recoil spring in a semi-auto pistol is a slam-dunk. [b]Do it[/]b, do it like yesterday!
As for the suggestion to also change the firing pin spring in the 1006... I'd do it, but I've heard that the safety/firing pin on the S&W 3rd Gens isn't to be taken apart by the faint of heart. I still have the new spring Wolff sent me with my recoil spring... but I've not installed it.