Need to know name of a 1970's toy gun...?

I remember these as a kid. These were gun-shaped rubber toys with wide mouth barrels, I think the guns were yellow and made out of soft, pliable rubber. You inserted a plastic ball about the size of a golf ball into the mouth of the barrel, and then you hold the gun in one hand while giving it a hard smack with your other hand. The resulting air pressure 'popped' the ball out of the gun, propelling it about 20 feet. Anyone remember this toy? Thanks!