If that cop wasn't a believer before I'll bet he was after. Weak hammer springs aren't a widely known problem.
One day I was fooling around with the strain screw and noticed how much better the double action pull was with it backed off a little
Next time I took it out I got regular misfires. I bet the same thing happened to that gun and maybe a lot of cartridges with primers a little harder than standard.
I once bought a few hundred rounds of surplus 9mm ammo. My Nephew and I decided to do a lot of plinking with the cheap stuff. We were shooting a Browning HP and a Beretta model 92, a real early one with the mag release on the bottom left of the grip.
The Browning which had never misfired or jammed, would almost always fail to fire on the first hammer fall but would fire every single time on the second. The Beretta would fire 100% of the time with the first try.
Nothing really wrong with the Browning, just a lot of sub machine gun ammo not really intended for pistols. It did make me like that Beretta tho.