I would bet money on this "Atlas Collectible Firearms" having some kind of connection to the notorious "Keystone Arms". Their Gunbroker ads are nearly identical, they're located only 37mi from each other, & they both get, or got, ridiculous prices for their wares.
Keystone Arms has been called out numerous times for his fraudulent behavior & nefarious dealings. Seems like they're not the major player they used to be anymore. Likely passed the torch to this Atlas outfit because the name got tainted up too much.
If this is true, I would never do business with them. More money than brains usually wins out though.