I got one of those scary black rifles lol, but it's not all black though. I built it myself around a stripped receiver, it was fun. As the saying goes, it's like legos for grown kids. If you're gonna get the ar, makes sure it's chambered nato round 5.56 coz you could also shoot .223. If it's chambered .223, you won't be able to use 5.56 ammo.
Sorry, can't help you about the S&W sport specifically, but the ar is a great platform, and superfun to shoot, especially if you get a longer barrel and a scope.