I'd say that is what they should focus on because that IS the problem. Stop trying to blame your change of focus on the NRA.
Can you honestly tell me that you think any of these folks committing mass murders are in their right mind? Maybe if we were using the resources we have to their fullest the criminals wouldn't be able to get guns through legal channels.
Granted, that won't stop them from getting them illegally if they really want one but it might make it a little more difficult.