upper + lower ?

[3turretsarmoury]

Greetings all , I bought a complete "AR" lower and a complete "AR" upper. The lower was transferred to me legally. BUT now when I assemble the pieces how do I change the status of the lower? Any help would be appreciated.

[M&P 40]

Call the CFO and advise them with the changes from a lower to a complete gun. They will ask barrel length etc and send you a new cert.

[3turretsarmoury]

thanks