Ok Since we don't register firearms here in AZ I'm doing laps in my head on how to legally be able to build my AR10 Pistol.....

Because with out registering the lower as a pistol it could be considered as an SBR to people that don't know the ATF rules on "AR Pistols" being based on the parts used in the creation of the lower. So ha anyone built one out here and if so how did they go about not getting fucked on it.

Every AR lower I've ever bought was an "other" on the form including my AR-10.

Just use a pistol buffer tube and don't shoulder it if you put a Sig brace on it.  Problem solved!

What is listed on the 4473?

 

This,  as long as your lower has never been configured as a rifle you are legal.