Correct! As a California resident who lives close to the border, I have attended many Nevada gun shows. You CANNOT buy a firearm in Nevada unless you are a resident. The only way an out-of-stater can buy a firearm in Nevada is pay for it then have the firearm shipped to a FFL dealer in California where the Federal paperwork and background check is done. Then you can pick it up after a 10 day waiting period. I know, because I have done this.
And as another poster pointed out, most "dealers" at Nevada shows are selling t-shirts or equipment, not firearms. There are usually a few antique dealers there too selling pre-1898 firearms for which NO paperwork or Federal transfer is required under law.
Do you [or anyone else here] know if Nevada law requires a private unlicensed individual [selling at a show, -or wherever] to see proof of state residency from his buyer?