Re: rear support in a sitting position
I use two sitting positions:
1. Backpack. I backpack hunt, therefore I have a backpack with me 90% of the time. With the pack standing upright in front of me, I grasp the forearm with my left hand, lay it on the upright pack, and pull into my shoulder. Right elbow on right knee.
2. Sling supported. Having shot a bit of Highpower, I am comfortable using a sling. With a scoped magnum, you can't shoot as low, or cross-legged, but it is still pretty good (and better, if combined with the backpack).