SIG posted information on how to submit your gun for voluntary recall.
https://www.sigsauer.com/support/p320-voluntary-upgrade-program/
You'd have to register and SIG will send you email on how to go from there.
The website is for U.S. Domestic Commercial consumers only. This excludes P320s purchased through police and LEO departments through Armed Professional Program (APP) or Individual Officer Program (IOP)
Also, do not send back with aftermarket parts