The problem with this is that there really isn't an argument for restricting the second amendment like that if you also accept that it should exist in any meaningful form. Either you accept that citizens can own firearms, with all that goes with it, or you don't; bringing in all manner of tinkering around the edges - closing the "gun show loophole", limiting magazine sizes, gun-locks etc - would do (and has done) very little to actually solve any of the problems that people cite about widespread gun ownership; the wrong people will still be more than likely able to get them.
Not really following this--are you arguing that the "right to bear arms" is the same as "the right to unrestricted access to any type of weapon I desire?" Certain restrictions make sense and certain liberties do not. I am in agreement with background checks and owner registration and restricting the type of guns and ammunition that can be sold (do we really need "cop killer" bullets on the market?), and likewise don't see the reasoning behind Texas law (for instance) that allows gun owners to carry weapons into the State Capitol and certain public schools.