can't speak to the affinity 3 but I did put a taran tactical spring in my first generation affinity 20ga and It improved the trigger substantially. Its been a few years so I can't quite remember the part exactly. When I bought the affinity initially it wasn't cycling flawlessly so I ran a good number of heavier loads through it. It still wasn't consistent with all shell brands even though the gun was kept super clean and lubed. I eventually relegated the gun to turkey duty only figuring it will cycle the big heavies just fine.
JT
Edit: just looked in the gunsmith box and I still have 2 springs: my original affinity hammer spring and
I also have the tartan tactical trigger spring with a self note saying that it made the trigger a bit too light (2lb. 12oz.)!
So Im guessing that I got the kit with both hammer and trigger spring and only ended up using the TT hammer spring.
Regardless the trigger was much improved!
As far as the gun function, the issues I had was with cycling the 2nd shell. Never had any misfire issues although the inertia guns are notorious for the bolt not rotating into battery if you try to feather the bolt closed.