There is no choke to adjust.
Both shotguns and cars have chokes. How they are adjusted depends of the particular shotgun or engine- we need more info to give you a real answer.
A barrel with a full choke.
System of changable shotgun choke tubes made by Mossberg. Accu Choke is their brand name. A shotgun choke is a means of reducing the bore size at the muzzle of a shotgun, to produce shot patterns that spread to a greater or lesser degree.
Cylinder bore- no choke at all.
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A pattern of a shotgun is determined by the choke at the factory. Some models have a variable choke that makes the user able to change the pattern.
They came in various barrel lengths and choke combinations. If it is not marked on the side of the barrel, you will have to pattern the shotgun to determine the choke
A shotgun barrel with a cylinder bore choke.
Yes- that is what the poly-choke is for.
No
To focus the pattern of shot.