Was there ever a Colt CAR-15 open bolt design?

[padredan]

the military had what was called xm177, i believe was the model number or car16, was a select fire weapon, not sure it was an open bolt, but had around a ten inch barrel with a flash hider and colaspable stock. more or less the forerunner to the m4. This would not be what you are talking about as it would be a class three weapon, therefore a machine gun.