There really is not a way to determine the exact date the weapon was made if there is not a serial number. However, this particular shotgun was created between 1958-1968, and is worth up to $700.
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.
Check the chambers.
Slugs will shoot safely through any choke but Improved cylinder or full cylinder should work.
No
A shotgun barrel with a cylinder bore choke.
Yes: A Remington 870 shotgun with a modified choke will shoot any commercial shotgun slug.
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
Amount of muzzle constriction
No
A poly choke is an aftermarket choke. The choke twists to different settings. It should have marks to determine settings around the collar of the choke