Hello, I've decided on a Mossberg 590 for my first shotgun, it will be used primarily for home defense, I'm looking at the 51410 model and am curious about the capacity, the website says 6 shot, is this 6 total? or 6+1? what is the maximum with a mag tube ext. with an 18.5 barrel? which extender is the best? thanks! Wanna kill these ads? We can help!