The U.S. M1Carbine in the foreground has, indeed, a M8 Grenade launcher installed. This allowed the squad the ability to launch smoke and signals without the loss of a semi-auto weapon. Rifle grenades and hand grenades with the adapter were a little heavy with recoil on a carbine, but could be used if required. The M1 Carbine could be fired semi-auto with Ball ammo with the launcher installed, the M1 Rifle with the M7 launcher could not. Post war versions of the M7 launcher, M7A1, A2, and A3 did allow semi-auto Ball ammo fire with the launcher installed. (Photo below)
![]()