Tam is trying the method of gripping the AR made popular by 3-gun shooters – i.e. the support hand as far forward on the grip as possible, with the thumb pointing toward the target. I started shooting this kind of grip a while ago, but I didn’t realize how much it improved transition speeds until I went out to Gunsite a few months back. There, when doing rapid swings from target to target, having the hand that far forward allowed me start/stop the gun a lot faster than with my hand way back by the magwell in the more traditional “modern technique” style.
A good way to see the speed improvement with the hands forward grip is if you’re using a rimfire rifle; the lack of felt recoil really lets you rock and roll on speedy transitions.