Stay at 300 yards, but lose the bipod and the bench. Change the targets to water-filled milk jugs. Stand up and shoot off-hand. If it's too easy, move the jugs out to 400 yards. If it's too hard, either move the jugs to 200 or try kneeling for more stability. Sitting is a little more stabil yet. A good exercise is to place the jugs at various ranges out to 400 or 500 yards with all shots inside 150 yards to be required off-hand. Then kneeling to say, 250 or so, then the remainder sitting. Use expanding soft-points, so the jugs will explode when hit. A few jugs should be inside 100 yards, but none closer than 50. Bring lots of jugs. When you are finished, leave the site cleaner than you found it. Obviously, if you are using an established shooting range, there may be restrictions on such improvised targets. Paper targets are essential for sighting in, load evaluation, trajectory plotting, etc. But reactive targets also have their place in marksmanship development. With a milk-jug, all hits are equal; like the heart-lung kill-zone on a deer. Sometimes, in hunting, it's better to be able to get a quick shot off anywhere into that zone, than to deliberate too carefully that the deer trots away because you tried too hard to be perfect. Still, you have to make a good shot and jugs are an excellent training target for that. Try it; it's fun, and a bit more challenging than you might expect.