Is the 26" rifled? I would use the 26" when I shoot slugs ex. deer hunting...yes, some people do hunt that way, some people can only legally hunt that way FWIU.
I have found the 18" barrel generally works good for home defense, shooting clay, and at the range I have shot 100 yard target off iron sights with a slug...not too shabby. Careful with steel shot, it seemed to be a bit hard on my barrel.
*posted a section on the wrong thread LOL*