Searched multiple archives and tried to get the answer offline prior to posting to avoid any controversy - am asking solely to stay on the right side of the rules/avoid trouble.

Bought a Sionics pistol with 11.5” barrel, and would like to buy a spare upper or two in different lengths (Colt 10.5, BCM 12.5, etc).

If I have the complete AR pistol in the same safe with my complete 6920, and buy/add two spare uppers to occasionally use with the pistol, am I out of compliance with NFA?

I was under the impression that legally I am ok, since there are no incomplete rifles and I don’t own/won’t buy any spare lowers.

If it’s a gray area then I just won’t buy any new uppers for my pistol.

Thanking you in advance ...