I'm pretty new to guns in general. Went to the range a few weeks ago and shot some pistols with an experienced friend. Started off with a .22 and then shot a 9mm. I was really thinking about picking up a sub compact 9 mm for a first handgun primarily for home defense. But talking to family, they expressed a shotgun would be better. Searching through it seems the obvious choice would be a Remington 870. What do you guys think about getting a 20 guage as a first shotgun / home defense gun. From reading it seems 18" is the way to go. Any thoughts?