So background checks don't prevent bad buys from getting guns, because bad guys - being bad - don't get their guns from sources that require background checks.
Thank you very much and you are correct
Bad guys can and do buy from private sells. Out of the newspaper,craigslist(even though craigslist removes the listing if they find it) and just from anyone who has a gun for sale that not a FFL.
If you as a private seller of a gun was required to make the buyer of your gun pass a background check it would limit the places a bad guy could buy a gun......and it certainly wouldn't be from a law abiding citizen because a law abiding citizen would require a background check.
This puts the criminal in a box so to say......he would have to buy a gun from another criminal or steal it. He couldn't buy from a store or a legal private sell.