I can't tell you how many novels I read that are loaded with grammatical error, worse, names of characters are wrong, details that were critical to one part of the story mysteriously change. The editor-class these days is woefully lazy, my eyes are frequently rolling as well.
I don’t think there’s an editor in NYC who has ever touched a gun. Same goes for Glenn himself. SOMEBODY who is knowledgeable on a given subject covered in detail in a book should be given an advance copy, whether it’s guns, airplanes, SCUBA or whatever.