There is an alternate course in building an AR - build a pistol. Basically a short barreled AR 7-12" barreled upper in an alternate caliber, with pistol buffer and SB15 type wrist brace. Some are already adding the LAW folding stock adapter to store in limited space.
The advantage is that you get the same parts, in a shorter handier size that is easier to wield in tighter spaces, such as hallways or behind barricades. You get nearly the same firepower, with a 10" barrel, ballistics are generally only 300 fps slower in 6.8. That's still over 2200 fps at the muzzle. All the controls can exactly match your long rifle, no confusion there and training or just plinking all goes to the same muscle memory.
It's a handy size for other members of the family, and easier to keep about the premises in places you may prefer. It's also legal in states that would otherwise restrict NFA short barreled rifles. And in a lot of states, you can travel with it by car - loaded, even - where a rifle might be required to be unloaded and cased. That is the kind of versatility few other firearms can offer for the power levels. Whether normally purchased thru an FFL or 80%, it's an option some might consider. It's about the same length as a Tavor overall, which is one of the benefits touted for that firearm.
