Are those MIM'd parts known to be a problem? When I had my trigger assembly apart last year, they looked physically fine (no chipping or anything obvious). They don't show up on "parts you should replace" lists either. I did replace the carrier spring and sear spring, but ended up back on the factory sear spring. The police one made the trigger far too stiff. The write-ups in favor of using it were to prevent NDs, but this is the first time I've heard it suggested to avoid drop fires. I might give it another try.
On my Brownells wish list...What I can say is that Brownell's sells a Remington 870P trigger group that is parkerized:
https://www.brownells.com/shotgun-pa...prod26466.aspx
Thanks,
Chris