King tells a good story almost always, and a great story once in a while. You can count me in with the people who don't crack open a King novel looking for technical data.
As for his being a liberal, that shouldn't be a surprise when you consider that he came of age in the sixties. If it pleases you to screen your authors for ideological purity, more power to you, but I do not. Their political leanings do tend to color their world view; but unless the political values are the point of the novel, I don't find them too disturbing in an otherwise good story.
As I said in another thread here on this topic, King is fascinated by guns, but also seems to be a bit fearful of them and know only a little about them. FWIW, you can often hear errors greater than his come out of the mouths of people, some of them behind the counter, at gunstores and gunshows.