First of all, Dr. Sleep is an excellent book; in my opinion one of Stephen King's best. I am a long term fan who first read The Shining in 1977 when it was published and have read a majority of his later books, including all of the Dark Tower series. I adore Stephen King.
Why oh why do top notch writers like Stephen King, who clearly conduct meticulous research on other matters, don't bother to do basic research about the firearms they write about? How about their editors? If you Google Glock .22 you will find 1) No such pistol exists (there is a Glock 22 in .40 S&W caliber) and 2) Glocks don't have a manual safety. (They are called the "Safe Action Pistol" because they have automatic safeties that are fully explained on their web page.) Don't get me started on why you would bring a pistol or deer rifle to a gun fight if you had access to other much better options.
Is our beloved Mr. King a hoplophobe? Are his editors? If they are, why include firearms in his stories at all when they are not necessary? Even if everyone involved in the writing, research and publication of Dr. Sleep has hoplophobia, that is no excuse for the lack of basic research that is only a Google query away.