Boiling down the legal mumbo jumbo
The section of law Navy LT quoted covers purchase of (acquiring) a gun ouside the state you live in. Fed Law. Can buy long guns from FFL in another state, and take them home. Cannot do that with handguns.
This is the reason you need to have an out of state handgun shipped to an in state FFL, and "acquire" it from them.
What you are talking about is loaning someone from CA a gun while he, and you, and the gun are in Nevada, right?
If thats the case, Nevada law is what applies.
Example: Your buddy from CA visits you in NV and you want to go quail hunting. He gets required non-resident hunting license, but needs a gun. You want to loan him a 20ga so he can go hunting with you. Is this ok?
It is, if Nevada law says it is. Whatever the Nevada law is covering loaning a firearm is, thats what you both have to comply with.
Reverse situation: You are visiting him in CA. You both have to follow all CA laws regarding firearms. And I believe, CA law requires a waiting period, check, etc., even for the loan of a firearm. (CA residents, please chime in, is this the case?)
All else being equal (and it almost never is) bigger bullets tend to work better.