what lengths do y'all go to on the first rounds after rebarrelling?

i got a new looking (yet advertised as take off) bbl from an auction site. the threads were completely unmolested, had the cheesy black mdl 12 fv finish on them, no sign of adhesive, and spinning the receiver on could in no way be accomplished by bare hands. it was a tight fit. a borescope inspection of the chamber and throat seemed ok.

i was going to measure brass b4/after neck od, datum, web. all the usual checks then i began to think.

two questions? 1. do i want to fire this using my finger, or remotely with a string? 2. if the bbl indeed had never been installed in a receiver, how was proofed? before finishing?