Got a lot of his shows on DVD. My best guess is a two inch model 10. I can clearly see that it has a round butt with the "flat" style cylinder release latch. You can see him apply thumb pressure forward towards the muzzle to open the cylinder. If it was a Colt, you would have to be pulling that latch to the rear to open the cylinder. No doubt about, Joe Friday is a S&W fan !!