Wow, that's a trick question! First, you'd have to get me to carry a Glock!
No offense to the Glock lovers in here. I'm a dedicated Sig man, ever since the military. But, if I'm about to enter the "fatal funnel" with my Sig in hand, it would be two-handed. Two handed, I have better control over where my weapon goes while I move my body behind it. I've found that in CQB, if you don't regard your loaded weapon as your axis, you're likely to either hurt someone else (the dreaded muzzle sweep) or yourself. Besides, what good would holding one hand out in front of you, do? If you're moving the way you should, no one is going to be able to grab your weapon and unless you're name is Clark Kent, your hand isn't an invulnerable body part. I've butt stroked people who were foolish enough to rush me as I moved into a dark room. Yes, I laid them down with a concussion but, I kept control of my weapon. Besides, what's a wee bump on the head compared to death?
If you have `cleared' all the rooms and met no resistance, you and your entry team have probably kicked in the door of the wrong house.
(Murphy's Cop Laws)
The greatest enemy of a good plan is the dream of a perfect plan. (Von Clausewitz)