SIG style arm brace conversion to rifle stock

[johnwilliamson062]

You can make a pistol into a rifle and then back into a pistol, but can you do the same for a SIG brace?

Could I use Sig brace as a rifle stock while I have a 16"+ upper installed, then switch to a shorter upper and us it as an arm brace in pistol configuration without changing to lowers actual configuration at all?

 

[Sharkbite]

If the gun is a pistol to begin with...yes