I working on my P220 that I converted to DA/SA from DAK.

I have a trigger pull of 9lb/2 lb.

The DA pull just feels really heavy.

I ordered the kit (17, 18, 19 lbs).

Has anyone tried these to lower the DA trigger pull?

Yes, but to me typically the juice isn't worth the squeeze.

The mainspring controls how hard the hammer hits the firing pin and thus the primer. A general rule of thumb is the lighter the spring the less consistent the primer ignition.

I stick to the factory SIG mainspring.

I did it with a P220 DAO, went to a 16 pound spring. Lowered the trigger pull from 12+ pounds to 6-1/2 pounds. Worked great for a couple of years, then started getting light strikes so I went to an 18 pound spring which brought the pullup to around 8 pounds. Works fine now.

I did the same thing. Put an 18 lbs. spring in there and not a single problem for at least 5K rounds.

I have noticed that the 17 and 18 pound springs seem to last about 4000 round before light primer strikes occur on certain brands of ammo. I run the 18#, but change it and the firing pin spring every 3000 (ish) rounds.