mkb42
The Mkb42 (Maschinenkarabiner 42 "machine carbine model 1942") was an early German assault rifle designed in 1940-1941 during World War II. It was initially designed by Walther, hence it was known as Maschinenkarabiner 42(W) or Mkb42(W). The more successful one was designed by Haenel, hence Maschinenkarabiner 42(H) or Mkb42(H). Chambered in 7.92×33mm Kurz, both were predecessors of the famous Stg44.
Visually speaking, the Mkb42 has longer, thicker gas tube that extends above the barrel compared to StG44.