I put the Wolff 5lb striker spring in my PM45. The stock spring was just a bit over 5 so it didn't make a tremendous difference.
I always meant to measure it again after shooting it some to see if it reduced a bit after being worked a bit but never got around tuit.
Could have just got a decent spring to begin with or as you say maybe the previous owner put one in?
In Memory of Paul "Dietrich" Stines.
Dad: Say something nice to your cousin Shirley
Dietrich: For a fat girl you sure don't sweat much.
Cue sound of Head slap.
RIP Muggsy & TMan
"If you are a warrior legally authorized to carry a weapon and you step outside without that weapon, then you become a sheep, pretending that JOCKO will not come today."