Exactly. Private sales are private. Without registration there is no way to enforce background checks on private sales.
Let them try for registration. BHO cannot do it by executive order and that dog won’t hunt in either house of Congress. He’s going to likely go after high capacity mags.
Good luck on that. There are probably hundreds of thousands of magazines in circulation out there right now with carloads more pouring out every day. A goodly percentage of them greater than ten round capacity, some (SureFire 60 & 100 rounds) a lot more. How could they ever expect to round them all up? I know that my battery of .22LR long guns w/ tubular magazines will pass muster but I feel sorry for anyone who spent $125 for a sixty round SureFire AR-15 mag, because the Feds will demand he turn it in so they can feed it to the crusher.