I went hunting for the first time a year ago and my uncle gave me the gun that he let me use (a single shot .17). Great! I'm a gun owner. In an attempt to further my interest in guns he lent me an old bolt action .22; later asking if I would be willing to give him $100, or $100 worth of ammo and just keep it (a steal)... now I own two guns... Then at the end of last summer he said he'd like me to "try" a larger caliber (.243) again asking later if I'd just keep if and give him $150.
Of course I trust my uncle, but he does a lot of trading and buying and selling with his gun buddies and a rural gun "shop" (some guy's living room converted). I don't have any paper work for any of my guns. One was a gift and my payment for the other two was more symbolic than anything.
If LE ever had a question, I'm sure my uncle would identify himself as the owner before me, but as far as I know he doesn't know their complete history. Also, it might look a little weird having 3 rifles that were all "gifts".