So I am posting this to share my experience with my first serialized Glock lower frame built so others can benefit from this information.
Remember, rules and laws are subjected to future changes, so always check the rules and laws in the future if you are reviewing this post beyond 2023 year
So a long story short, I wanted to build an optic ready Glock 19 clone. I ordered the SCT19 serialized frame from Brownells and got it shipped to my FFL. When I picked the frame from my FFL, he did not issue an RI60 saying that he doesn't know what I am going to build a gun with barrel length, caliber etc. And that I have to register the gun once built.
I ordered the slide from PSA and some lower parts to build the lower.
I then contacted my local police department where I register my handguns at the AA police department and specifically the officer that enters my registrations. I asked him how to go about the registration and he confirmed that seller and buyer on the RI 60 form is myself (since I have a CPL), and advised to write next to the purchaser signature "Assembled from Parts" to indicate it is a build. He is a great officer and always answers my questions.. Sent my RI 60 registration and all set. I hope this helps alot of people asking questions about how to go with a serialized frame build project for registration.