The quote below is from Chapter 3 of Ruthless - The Blackwell Files Book 2. It is a book of fiction by author Steve Freeman. He says this series of novels are from "his firsthand knowledge of military service, the tech industry, and the diverse cultures of our world".
After a bit of research and the purchase of a masterfully-produced set of faked credentials, (the killer) used the forged documents and a Visa gift card to buy a used Smith & Wesson through one online retailer, and a compatible silencer via a different online site. (The killer) had the purchases shipped to an abandoned house, allowing for a an anonymous, nighttime pickup of both items.While our enemies in the gun prohibitionist movement would like to believe the above is reality, it is utter fiction. You know it, I know it, and the author of the book hopefully knew it.
Unless it was an intrastate transaction, firearm sales go through a FFL and get a NICS check before delivery to the purchaser. As to the silencer, you are looking at a $200 tax stamp plus a generously estimated 6 month wait for the background check. You also have to submit photos.