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The Highsmith Rifle Drill is designed to push shooters' limits on strong side to support side transitions with the rifle, proper barricade kneeling techniques, and lateral movement while firing - from both the strong and support side.
This one is a personal favorite of mine. Transitions between strong and support side take quite a bit of practice - as does accurately (and comfortably) firing from the support side. Considering the alternative (exposing half of your body to hostile fire), I'd consider practice on this one to be time well spent.