There used to be a few people with a heel fitted to their gun, not so many now. I think if you were to use one for support as a palm shelf it would in most cases be too far back and too far away from the balance point. I hear it's good to have your left hand supporting the gun slightly behind the balance point, but that is still usually just forward of the trigger.
Anschutz 2013 MEC1 .22LR
Miroku 3800 12bore