Continuing with our study of field shooting positions we will discuss the sitting position. In the field, sitting will be far more useful to you than prone. A few weeks ago we ran an entire 100 - 1000 yard sniper class shooting almost exclusively from sitting. It is, once understood and developed, almost as accurate as prone. As well, it is far more adaptable in the field when dealing with broken terrain and/or elevation changes.
The sitting position most conducive to accuracy vis-a-vis bone support, muscle relaxation, and stability, is with the feet drawn up under the knees. Bring these as far as possible to gain elevation of the knees. This creates a shelf for the elbows to rest. Bring the support hand into position as needed. In this photo, I am shooting at fairly level targets, but if I was shooting at elevated or low angle targets, I would ammend my hand position as necessary. Popular CQB rifle shooting videos to the contrary, when shooting at distances, the elbos must be supported for the best results.
One issue with sitting is that some out-of-condition shooters may not be able to actually get into position. The sitting, however, can be practiced at any time even without a rifle. This will enhnace and increase the back flexibility necessary, which in turn will not only make the rifleman a better shooter, but will give him better health and mobility through increased flexibility.