Acquired Pre-Cancelled Collection - Questions

I've started calling those precancels with full original gum, never hinged as "as issued" - "ai" for short. Pretty much sums them up - and as for "Bureau's , unless it's way out of my financial league or if never found "as issued", that's how I collect them - "as issued" . . .(little caveat here - right now, all I'm collecting is stamps from the Americana Issue) . . . I've got three from the Americana Issue that I'll keep in my collection as "used" : Philadelphia, Pa. 1581-81, Richmond, Va. 1614-81 and the 13 cent narrow precancel 1st class 1618-2.2 . . .