Want to stay legal. SBR question
I have a legal DPMS 20" AR-15, which I now want to convert to an SBR.
Great, I have to get a tax stamp to create an SBR, which is fine. Is there any reason that I cannot use a pistol upper to create a 7.5" AR-15 SBR?
Now I know I cannot install the upper until I register and pay the tax stamp but if I file the paperwork and order the upper, is that complying with the law provided I wait on the Tax stamp prior to installation of the upper?
The object is to stay legal. If it's not possible, I don't plan to pursue it.