As far as I know, all guns are test-fired at the factory. Any rounds fired at the factory (and for a handgun, the total will probably be between 2 and 6) do not make it a "used" gun. It is BNIB when you buy it, as long as the dealer or distributor did not add a few rounds to the total...and honestly, you probably would never know unless you were an employee of the shop.
In similar manner, your new car was driven from the assembly line onto a storage lot, then onto a truck, then off the truck and onto the dealer's lot. It might have 1.4 miles (or .6, or whatever) on it when you go to look at it at the dealer's showroom. If it has 126.4, that is different.
I have read that Corvettes and some Honda motorcycles are also chassis dyno'ed before leaving the factory.