When I first had a shotgun barrel threaded for choke tubes I only owned one shotgun, but I had three barrels for it, a 26" IC, a 28" M and a 30" F. it was a Remington 1100 my Dad gave me for my 16th birthday. I had shot many patterns with those barrels and was accustomed to what I thought a typical shot pattern looked like, with it's very "hot core". I had the 30" F barrel threaded and bought a set of CompNChoke tubes. I commenced to shoot more patterns to see if there was any difference, on paper, saving and labeling the patterns. I was astounded to actually see a difference I could quantify. Simply put, there was less of the total percentage of pellets in the hot core and more in the outer 10" "ring" of the pattern. I immediately realized that this was a good thing for clay target shooters, especially, as it decreased the chances of a clay slipping through the pattern in the periphery.
I took the rolled up patterns to the office of the owner of CompNChoke and showed them to him. He was surprised I had gone to the trouble of patterning them that thoroughly, but smiled when I showed him evidence of what I had seen. He may have been correct, or he may have been wrong in what he said next, I don't know. But, he said that was the result of precision machining in the choke internals, and said that was something that was sorely lacking in the Remington's fixed choke barrels. Obviously there are other choke tube companies, and fixed choke barrels, that are choked with precision and care, and will deliver the most uniformly distributed patterns possible, but I'll go to my grave knowing the difference I saw between those chokes and MY old fixed choke barrels.