For sight-in I usually use a large denim bag filled with scrap plastic pellets (old injection molding resin) with a canvas or leather pad. 2 hand hold with trigger guard and hands buried in the bag. Bottom of non gun hand touching bench. Elbows supported.
For hunting I use my backpack on a log or a rock. Very solid. In Africa (and prepping for the trip) I shot from a bamboo tripod with a homemade, clamp on wrist rest. Worked great but too wobbly for sight -in. Good for open field varmints.