I forgot to address the issue of lubrication of the slide, rails and barrel exterior.
I use a very very thin coat of marine/white grease to minimize wear on the rails, slide and outside of the barrel. Oil is good, but unfortunately it migrates if left sitting for a few hours or days, giving you a false sense of lubrication. In theory the downside to using grease is that exploding particles will also stick to it. But in practical use I haven't seen any extra dirt.
You can get marine grease at your local auto parts store for $2-3 for a 8oz tube. You can spend more on "specialized" gun products but none will be as good as those targeting automotive applications. The reason I use the marine grease because it is white and wont stain my hands or clothing like other black grease.
