Strangely enough, I have tried that tuck the elbow and balance the rifle on your fingertip routine and I felt it was terribly insecure.
Extended arm for me and just let the rifle sit on the hand works well enough.
Well, I must amend that last statement. When I was shooting the 8 bore and the 4 bore rifles, I hung onto either of them really tight, else the recoil would have sent them flying backwards, up and over. 400 grains of Fg does things like that when it's pushing a 1,450 grain round ball. I wonder why I ever thought that was fun? Maybe because it felt so good when it stopped hurting.