Like most people his political views changed over his long life. I would say they ran from National Socialist to Libertarian.
You'd be wrong.
I always felt that he was more of a Fascist, or probably something like an 18th Century 'Enlightened Despot'.
As would you.
Any truly serious Heinlein student would dismiss both of those views at first glance. Heinlein was very deeply disturbed by both national socialism specifically, and totalitarianism in general. He was an elitist, clearly, but not in the way that some elitists think that they should run everything as a dictator. Also, please understand, several of the fictional governments/social systems that he wrote about were never intended to put on a pedestal as an ideal way to run a country/world (with the possible exception of the Twain-inspired gondor-analogue from Starship Troopers). If you doubt this, read Grumbles From the Grave, or the new biography that's just come out. It's quite clear. He was pro-military, and vehemently anti-communist, both to extremes. This is where some people get the idea that he was "fascist", but if you simply look up the word itself, you will see how absurd that comparison is. For a more detailed rebuttal of this, see Spider Robinson's essays.
As for Heinlein being a gun guy, he was an expert marksman. We have evidence that he shot a stray cat that was attacking his family pet. First shot hit dead on, after several years of not shooting (lack of shooting practice most likely due to his poor health). He also taught marksmanship at some point, if memory serves, though that i'd have to consult my notes to confirm.
Heinlein was definitely "one of us". He liked just about ALL personal weapons, to my knowledge. He also studied unarmed fighting, and his wife Ginny was a Judo expert. He fenced competitively, and not with the flimsy little blades we modern fencers use. The sabre in that day was an honest weapon, though it did lack an edge. The guy was the original "survivalist" (not a dirty word in my world), or would have been, had his health been a bit better. He also wrote MANY books and short stories that referenced firearms, not just the ones involving mass combat. If anything, there are probably more firearms of various sorts in his canon (pun intended) than blades. In one case, there was even a gun/sword cane. I'd also be willing to bet that he owned more than just one .380 pistol. That one we know about because he used it to kill a cat, and he wrote his editor about it. He undoubtedly kept more hidden away. The man built his own concrete bomb shelter for heaven's sake.