Depends on what you are shooting. A Modified Choke gives a medium "squeeze" to the pellets passing thru the end of a shotgun barrel, thus producing a denser pattern of shot. A full choke squeezes more, and a cylinder choke, not at all. A denser pattern may mean slightly greater range with birdshot- but it will also mean the shot pattern is smaller, reducing the chance of hitting a bird in flight. In general, modified is a "middle of the road" choke, and fairly useful in hunting- but not in skeet, trap, or sporting clays.
Cephalopods
A skeet choke is a screw in tube that is inserted in the end of a barrel of a shotgun, the main thing a skeet choke does is changes the spread pattern of the shot from the shell, since its a skeet choke it will make the spread very large so that you can hit the skeet easier.
Univalves
Have it checked over by a gunsmith first.
No risk if it's a modern gun in good condition with a shell of the proper gauge. I wouldn't try in damascus barrels or guns with a "poly choke".
Depends on the choke, load, barrel length and who made the loaded round.
A Diatom.
False
paramagnetic.
You will have to provide a detailed description of the action type, ALL markings, shell size, barrel length and choke, finish
They breathe through a single gill
You can get a choke gauge at any gun shop. However- some of the older guns give a slightly off reading due to wear. A dime should fit tightly in a full choke barrell. "Old hand" way of checking. Break open the gun as if loading. Choke should be stamped on the inside just below where the shell would go.. Solo