Proper cleaning and lube of the bolt group and trigger goes a long way to making your rifle shoot well. If your rifle shoots well, some good optics.
Unless you are on a SWAT entry team, leave your fine rifle as a fine rifle! If you still think you need CQB weaponry, find a nice 870 Shotgun and a good handgun. No need to have a too long of barreled, semi-auto sub-machine gun for room clearing!
Ivan