Overall I'd agree with Alexsey(H-D) except point that slugs wear the chokes. I shot mooses, bears and boars from smooth bore double gun and big issue in this case is barrels regulation. You can't regulate barrels yourself, but everybody can choose the right double with minimum cross at aprx. 50 yards. And its very important the POI from the first barrel you shoot, under or left or whatever. If the gun shoot well, but front sight doesn't match, replace it to right one, thin and better something like TruGlo. Install rear sight, if needed.
12G double gun loaded with heavy Brenneke slug or such is very effective spopper and vital at close distance up to 25 yards, if you going to shoot dangerous animals.
