The argument with gun control here typically has little if anything to do with criminals obtaining guns. You can make buying any gun period illegal and criminals will find a way to obtain one. The issue that is argued about is that most mass shootings here in the US are done by individuals who obtained their gun legally despite a long history of mental illness or potential ties to extremist terrorist organizations. The debate in a nutshell comes down to whether or not it is okay to deny people the ability to purchase a gun b/c of these factors or if it is infringing on their second amendment rights.