try switching eyes as you clear left and right corners. that's if you are using a gun without a but.
when using a butt enter the room with your gun at a 75degree rather than 90 and keep an eye on your front site. nothing else matters in cqb less they have a hostie.
clearing your corners is done by stepping back from the corner and clearing all slices of pie before rounding. This creates a more shallow angle and allows less of your body and more of your vision.