When I was enamored with our amateur PPC league, I took my well-worn 4" Model 66 ND and had it rebarreled with a factory new 6" barrel. It worked quite well for that purpose until my interest in that game waned and my amphibian brain fixed onto something else. When that gun became the basis for Project 616, I was able to sell the "surplus" barrel to a member of this forum to recoup part of the cost of the new iteration of my long suffering revolver. That 6" barrel is a whole lot less common than the 4" in my experience because so many of the latter were found in the duty holsters of law enforcement officers through the '70s and '80s or later. They were and are not inferior to the 4" except maybe for a uniformed carry, and for most folks, not even then. I would suggest they are superior for all around civilian use, but that's JMHO, and of course YMMV.

Froggie