This is an original US Heavy Padded GRISWOLD M1 Garand drop bag. It was worn by US paratroopers when jumping with their M-1 Garand rifle. The drop bag is marked "CASE INDIVIDUAL WEAPON PARACHUTIST M1950". It was manufactured by JQMD.
This M-1950 or Model 1950 was an improvement over the WWII drop case, as this case is long enough to accommodate a M1 Garand rifle without breaking it down into the three main parts. The Griswold bag was developed during WW2, for a Paratrooper to carry his rifle in during parachute jumps. The bag was strapped to his parachute harness under his reserve chute for easy access. The first model required the rifle to be taken apart, then reassembled after the Paratrooper reached the ground.