So, eventually I would like to get a longarm for home defense here in the state of Colorado. I have been almost entirely a pistol guy for the majority of my time as a shooter (save my 870 Wingmaster which is currently serving in this capacity). However, I would eventually like to get into longarms with a mind towards self defense in the home.
While I have plenty of grandfathered 17 round 9mm Glock magazines, I can't legally purchase new magazines in Colorado with a capacity greater than 15 rounds. With this in mind, what home defense longarms would y'all recommend? I have mostly been leaning towards an automatic shotgun (either a FN SLP or a Benelli of some stripe).
Are there any centerfire rifles I should be considering? or is the shotgun the way to go in my situation? I will also probably move into bolt action rifles/long distance shooting in the much longer term but short term I'd like something that I can use for more 'practical' purposes...