Congress penalizes the law abiding for being law abiding. The odd similarity between these mass shootings(besides the guns, obviously) are the people pulling it off are insane. Rather than find a way to keep crazy away from weapons, they blame the weapon. They then wrap up gun control in "protecting the children" flags and ram reactionary legislation through to 1. remove the right for Americans who have broken no laws to possess weapons or 2. cover their own ass so when these measures fail, they can say "well we did something, right?".
You do have to wonder, however why Americans cannot possess automatic weapons, but our beloved government can sell automatic weapons to mexican drug cartels. Odd, how that works.