I'm just thinking extemporaneously and have no numbers or facts to back this up, but I think you'll find a lot more social-darwinists amongst conservatives than you will liberals. Where a conservative might look at a social problem and either just blame people for being stupid or lazy, or if more progressive, ways to improve the odds of someone being able to pull themselves up by their own boot-straps so to say, a liberal will look for external blame and try to find ways to give someone a helping hand up.
So, from that perspective, they (liberals) look around and say "Oh my god, there's too much gun violence, we need to do something. I know, less guns would mean less gun violence.". Sometimes, I'm not entirely sure they aren't wrong. I certainly don't subscribe to thinking that if everyone carried guns, mass oubreaks of violence wouldn't happen. I think the primary shooter would kill fewer people, but you'd see a lot more collateral damage done as all the would be Wyatt Earps gun him down. When it comes down to it, I just don't like giving the federal or state government the power to toss aside one of the bills of rights.
As an organization, the ACLU is pretty consistent on the matter though. They are just as likely to fight a gun ban as they are to support a white power demonstration in Skokie.