When using a sitting shooting position, what provides support to the arms?

In the sitting shooting position, the legs crossed at the ankles serve as a means of support for the arms. This position stabilizes the shooter's frame and creates a more steady platform, allowing for better control of the firearm. By crossing the legs, the shooter elevates the knees, which helps in resting the arms on the thighs. This technique allows for improved shot accuracy, as it minimizes any movement that can be caused by muscle fatigue or instability.

In contrast, while the ground can provide stability, it typically does not directly support the arms in the sitting position. A shooting stick is an external tool that can aid shooting but is not used exclusively in the sitting position and does not relate directly to the question. The shoulder, although important for bracing the firearm, does not provide direct support for the arms when sitting and raises more issues regarding mass and body tension that could affect accuracy.