of all the bags,and rests i used over years,3 sandbags like you said is best.at the public ranges at our club, i made up a bunch for each station. i see shooters come out with real nice adjustable rests etc. guess what.after a few shots,they move them out of the way and grab the 3 sandbags,ha.its funny to watch.i made some of my bags with old sweaters using sleeves and sowed theends closed.they make the best restfor shooting, i feel.i have adjustable front rests too but like sandbags .