Now I'm confused again. The more I learn the less I know.
..... Some gun writers tried to convince us that chokes in a shotguns aren't even necessary any more. Now I'm being told that at normal ranges it really doesn't make a difference.
Is there a simple explanation?
The more you choke a gun the more uneven the pattern becomes. You can't smash hundreds of shot pellets through a constriction at the speed of sound without deforming the shot to some degree. That is one reason harder shot shoots better patterns, i.e. being harder it resists deformation.
There is an excellent article written over 100 years ago by Sir Ralph Payne-Gallwey, a noted shooting authority in his day who is credited with many thousands of birds shot. He explains the advantages of cylinder bore guns and choked guns. His words are still true today. The article is called
The Merits of Chokes and Cylinders, as Applied to Their Effect On Game and Suitability to the Shooter. If you want to read the entire article, three parts, you can find it here:
The Merit of Chokes and Cylinders Here is a small excerpt:
"There is no doubt a choked gun shoots with more force than a cylinder, though only slightly; but I have never found this superiority exist to such an extent as to cause any noticeable effect on game at sporting-ranges, though at the target the full-choke will penetrate at 40 yards a couple more sheets of paper than the cylinder.
What a choke does is this: it carries its charge of shot closer, and so, of course, puts more pellets into the game than can a cylinder; and this attribute at a long distance naturally tells in favour of the choke, provided the aim is sufficiently correct to place its smaller shot-circle on the mark. Up to 35 or 40 yards (the latter being a long shot), a cylinder or a slightlychoked gun is far easier to hit with, and therefore a more deadly gun to use, than a full-choke, and either of the former will place amply sufficient pellets in the game to stop it well and neatly without wounding, even at a longer distance. At 35 yards a full-choke will place in the game half as many more pellets than are required to kill, which not only spoils its flesh for the table, but prevents the bird being kept till fit for cooking, from its perforated condition.*
* I have seen driven partridges—birds which a shooter is often obliged to fire at within 18 to 20 yards or not at all— so shattered by the mass of shot plastered into them by a full-choke that nine to the dozen were best suited for ferret-meat! Last season, for the sake of experiment, I killed six driven partridges with a full-choke at the ordinary range at which these birds come over a high hedge in a level country, and on reaching home I counted the holes drilled through their skins, which were respectively, 37, 33, 32, 29, 21, 19. The next day I killed six more birds with a cylinder at the same stand, and at the same average distances; result in pellets to birds—17, 15, 12, 12, 9, 7. The latter six birds were brought down as clean as could be wished, and dropped without a flutter. These were, however, all fit to eat, the previous six being only fit to drink in the form of soup." 
