Some shooters just love to grab onto the front of the magazine well to help steady an MSR when shooting off-hand. But positioning the lead hand out along the hand guard yields better results. This is the reason why hand guards that extend out 15 inches or more are so popular among competitive MSR shooters.
Grasp the MSR with your dominant hand cupped underneath the hand guard and your thumb pointed downrange. With your other hand grip the rifle far enough forward so that your arm is straight and your elbow is locked. This creates strong rearward tension as you pull the rifle back toward the pocket of your shoulder. This keeps the rifle in place and allowing fast, accurate shot placement.