Howdy
Those machines are called CNC (Computer Numerical Control). They have been around for a long time now. I was working on one that went all the way back to about 1968 a number of years ago. Virtually all the gun makers are using them now, as well as manufacturers of all kinds of products. CNC allows parts to be made nearly identically, removing most human error. They also allow parts to be made much quicker. Generally, one operator will be controlling several machines at once.
I saw some in operation at Remington a number of years ago, saw some at S&W a couple of months ago. I would be very surprised if Colt was not using CNC to make parts. In fact, I guarantee they are using CNC.