Without a Federal UBC law it all depends on State Law. In Texas its a non issue. I've gifted the Best Man at my wedding, his son for his graduation, my nephew a rifle for his 18th birthday and pistol for his 21st, I've bartered guns for CNC machine shop work, and a painting contractor, etc. I've also been on the receiving end of these transactions.
The Federal straw purchase issue can get sticky, especially with relatives or close friends, just be sure there is no paper trail for a recent purchase and an equivalent transfer of money or services to the giftee. There is no BATFE guidance that I'm aware of as to how long you you have to hold it before its "yours" to be free for sale or trade or gift without being considered a "straw purchase". This is a big issue at gun shows with a wife buying a gift for her husband, he picks the gun, wife/girlfriend tries to buy for it, and all the "straw purchase" alarm bells go off at the dealer's table.
If you are paranoid, just pay the transfer fees and do the background check.