For starters, you gun has to be mailed FFL to FFL, that means your local gun shop to the local out-of-state gun shop of the trader. After that all state and federal gun/licensing laws apply.
As for your second question, people have different needs and wants. It is not unusal for someone to go from a larger caliber to a lower caliber gun and vice versa if that's the gun they want.
As for your second question, people have different needs and wants. It is not unusal for someone to go from a larger caliber to a lower caliber gun and vice versa if that's the gun they want.