The Beretta 92FS appears to be the sidearm carried by the Military Police personal at Hawkins National Laboratory. The use of the pistol is anachronistic since the M9 pistol didn't enter U.S. military service until 1985, while the show takes place in 1983. It would be more accurate for them to be issued the Colt M1911A1 like the government agents. The majority of these pistols in the series appear to be replicas.
Error creating thumbnail: File missingBeretta 92FS - 9x19mmError creating thumbnail: File missingA Military Police officer holds his Beretta M9 and a government agent holds his Colt M1911A1 on Chief Jim Hopper in "Chapter Five: The Flea and the Acrobat" (S01E05). Note how these appear to be either dummy or airsoft replicas.
Jonathan Byers (Charlie Heaton) takes his father's Smith & Wesson Model 10 when he and Nancy Wheeler (Natalia Dyer) set out to find the monster in Myrkwood in "Chapter Five: The Flea and the Acrobat" (S01E05).
Error creating thumbnail: File missingSmith & Wesson Model 10 Revolver - .38 SpecialError creating thumbnail: File missingJonathan steals a Model 10 from the glove box of his dad's Oldsmobile 442 after his brother's funeral while Nancy looks on.Error creating thumbnail: File missingJonathan practices firing the Model 10 at some beer cans. "I'm trying to hit the space between the cans."Error creating thumbnail: File missingNancy takes aim at a beer can during shooting practice with Jonathan. Her "golf club-style" grip seems unorthodox, but it's probably safe to assume that most high-school girls don't know how to properly hold a handgun. Despite this, she hits the can on her first shot.
Heckler & Koch MP5Ks with PDW stocks attached are also used by agents. Since the show takes place in 1983, this is considered anachronistic since the MP5K-PDW variant was not developed until 1991. Some of the stocks actually looked more similar to UMP stocks, making them even more anachronistic.
