Can you guys help me out here? I want to form1 my AR pistols. They both have braces on them now, one has the SBA3, and the other has the SBA4. Both are adjustable as I'm sure you're all aware. Once legally stamped SBR's, they will get adjustable carbine style stocks. How does one measure the OAL of the rifle/pistol when filing the form1? Fully extended, completely collapsed, end of buffer tube without the brace? Thanks for any help.