Originally Posted by Adam
Prone means lying on your stomach. Lying on your back is called supine.
Reverse prone would mean lying face down with your feet toward the target. I'd love to see someone hit a target that way.
I've not only seen it, I've done it
They had a vertical target out in the Anglo American one year and that was the best way to take the shot (laying on your back with your beanbag under your shoulders).
The rules say that you can't rest your back against anything that isn't part of your bag, so it was necessary to put your bag under your shoulders so that you met this rule.
There was also a lad at the Worlds one year that shot every target laying on his back with his rifle rested between his knees. I wasn't there, I was told about it by Calps.