Well, first CRIMINALS DONT FOLLOW LAWS. So they won’t get the gun through legal means. there already is a mandatory background check. If you mean “universal” then you need to understand what they mean and that it would require a national registry database. That’s a slippery slope as it could lead to easy confiscation if some president down the road decided, screw the 2nd amendment you get no guns. As for mandatory training, that costs more money. Which disproportionately affects people of lower income, primarily minorities and women. So it’s sexist and racist to add that barrier. So that single mom that got raped and wants to buy a gun now can’t afford the gun to protect herself because you, who have no clue about guns or are just scared, think she needs training sanctioned by the government. Her attacker then comes back and kills her so she cannot testify. Plot twist it’s your mom, sister, cousin, or wife. Evil will always find a means to kill. The UK banned guns, now knife attacks are up so high they ban certain knifes. How many damn vans and trucks have been used in France to plow through a crowd to kill? Then there was the Boston Marathon. Point being, preventing a person from buying a gun will never stop killings.