Speaking as a liberal, NRA member and gun owner, I can directly relate to some of the points here. Most liberals automatically assume that the NRA is an organization that is thoroughly republican and conservative, and they simply wouldnt be welcome. I still feel that way to some extent, and I don't get involved in political discussions at the range, especially when people start talking about "liberals" like I'm some kind of freedom-hating, terrorist-loving idiot.
Many liberals are however frankly scared of firearms, mostly from lack of information and exposure. For your typical urbanite liberal, the only time they hear about guns is from crime reports, or reading about kids with AKs in Africa. In their minds, guns kill people, and they don't want people to be killed, so less guns means less killing. I of course don't need to go into that fallacy here.
Every time someone is ranting about liberals, and painting them with a simplistic brush, they are working against their own cause, no different from when a liberal thinks of gun owners as yee-haw gun-crazy rednecks. I always find it interesting how Heston's now famous line on the stage of "from my cold, dead hands" is seen as a rallying cry from the right, and the cry of a zealot from the left. I see it as a bit of both. It's the duty of BOTH sides to be able to be objective and discuss their viewpoints in a constructive manner. Most liberal friends that I've taken to the range ended up interested, and that goes a long way to making them see firearms in a completely different light.
A country without different political viewpoints would descend into fundamentalism. It's an important part of the process. Listen to both sides, I believe the truth is usually somehwere in the middle.