Have several ARs and some like rifled like the Sig MCX, MPX and 556. Sig 556 is heavy but with the piston it is by far the softest shooting 556. For longer distances up to 600 yards 5.56/223 does well. For home defense it over penetrates is loses a lot of energy as barrels get pistol lengthand is not the greatest stopper. 300 BO is great for shorter ranges ( up to 250 yards, used the same bolt and mags as 223, has good short range stopping and works well suppressed. 350 legend is a 300 blackout on steroids, 450 bushmaster makes them all seem wimpy. The trick is get an AR in one caliber and uppers in other calibers and use which ever round works for what you are doing.