I don't worry too much about the capacity on the 870. Its an ole workhorse farm/ranch gun for dispatching snakes and possums around the hen house, and pointing drunken college/high school kids who stray on the property, kicking their heels up a little too high to the most direct route back to the road.
For SHTF, I have the Saiga/ drums.
The dimples are no big deal there are some utube videos that show what a snap it is to swap them out...
Best to wait till the Gov figures out what they are doing with all the crazy stuff first!