M79 grenade launcher, A.K.A 'blooper'.
The M79 was supposed to let a soldier launch grenades both with extreme accuracy and at a very long range.
The M79 was however, as heavy and cumbersome as a standard rifle, and since it could only fire grenades, it couldn’t be used at close range or for self-defence.
Thus the army created a special grenade shooting buckshot ammo (like hunting shotguns use), but even then, a soldier with an M79 often had to use his 1911 in the most dangerous of moments.
That was therefore, the main reason why the Baker teams hardly ever used it.