How much muzzle constriction there is.
If you mean a choke bored barrel, it designates the amount of constriction a shotgun barrel has.
Modified Choke
A barrel with a full choke.
They probably denote what choke the barrel has.
the barrel is narrowed at the muzel for a tighter shot pattern.
This means there is no "choke" or narrowing of the barrel at the muzzle.
How much the shot is constricted as it leaves the barrel.
At the end of the barrel
They are a code used to denote choke size.
choke of sears model 20 12 gage plain barrel shotgun has 3 stars on barrel
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
To remove the barrel choke on a Mossberg 600AT shotgun, first ensure the shotgun is unloaded and clear. Use a choke wrench or a suitable tool to unscrew the choke from the barrel’s muzzle. Turn it counterclockwise until it is completely free. Once removed, you can replace it with a different choke or leave it as is, depending on your preference.