I don't know why there's really opposition to universal background checks. It just seems like common sense to me. If I were to ever sell a gun, I'd want to make sure it wasn't going to someone who couldn't legally own it, even if I had no liability for whatever they did with it. Gun shows and private sellers will work out a way to make it happen. It's as simple as finding an FFL holder with a computer and phone.
There should be a national mental health registry that can prevent someone from purchasing a gun. It should be somewhat difficult to get people on the registry and they should have a process that they can go through to get off of it.
There should be an armed police officer at each school. We already have one at each high school and middle school in my area. I see absolutely no reason to not do this, other than having to fund an extra officer's salary each year, which is a drop in the bucket compared to the salaries of all faculty and staff at each school.
Semi-automatic weapons with various features (ex. bayonet lug, detachable magazine, flash suppressor, pistol grip, second hand grip, etc.) should not be banned. There is no proof that this will affect crime at all and limiting the rights of people to own scary looking guns is just a security theater type action, similar to TSA screenings. I feel like a majority of the people on the other side of the AWB debate just don't have a lot of knowledge on the topic.
Limiting magazine sizes will also do nothing. This only impacts mass shootings, which are a ridiculously small percentage of shootings in the US. Swapping a magazine only takes a couple of seconds. People talk about rushing an active shooter while they reload, but it just doesn't happen. Mass shootings almost always end with either the shooter killing himself or being shot by a citizen or officer.
Guns are not just for hunting and sport. The argument that you don't need a semi-automatic gun for those types of things has no bearing. Read the 2nd amendment for the major reason that the right to bear arms exists.
Using children and tragedy to play on people's emotions - people who don't even have the requisite knowledge to know what they are opposing or supporting - is despicable. The left and most sensible people said this about the Patriot Act. Some of these renewed gun control proposals are in the same vein - overreaching measures that have no demonstrable effect other than to infringe on the liberty of citizens.