Ah, the old "gun control laws can't prevent all gun deaths" straw man. They just can't argue this honestly, can they? Well, let's try.
1. The goal of gun safety legislation isn't to prevent all gun deaths. It's to reduce them.
2. The goal of the assault weapons ban and high capacity clip ban is to reduce the number of deaths in mass shootings.
3. In the case of the Virginia Tech massacre, the shooter was mentally ill but was able to acquire firearms. 92% of Americans favor mandatory background checks for all gun purchases, and the NRA opposes them -- because after all, they won't prevent all gun deaths.