The Heckler and Koch MP5 has more than 100 variants and has been in production since the mid 1960s. It uses a G3 design with a selective fire delayed blowback system and fires up to 900 rounds a minute using propellant gasses to recharge the next round. Muzzle velocity can reach up to 1,394 feet per second depending on the variation. The effective range is limited to a maximum of 200 yards, which isn’t bad considering it is intended for close-quarters combat. The barrel has a rear peep sight and runs a 1:10 – inch twist, varying in length from 31.1-13.7 inches depending on the model. The subsonic rounds and short barrel length improve performance and reliability. Traditionally, the MP5 fires the 9×19 Parabellum, .40 S&W, and 10MM auto, but can be modified to chamber the rimfire .22 with up to 40 rounds. It’s currently produced in 12 countries and used in more than 100 countries.