I know some P320s have no safety lever spring but when I was taking mine apart to install a new trigger the large pin popped out a little. I didnt notice a spring anywhere in the vicinity but you know how springs evaporate.

Mine has the upgraded/recalled trigger if that makes a difference.

That spring was deleted in the new models.

are replacements available from Sig?

I really feel that spring should be installed - especially in a system as crucial as the safety!