You don't use lower rings or a shorter base because your groups are too high. You do it so you can get a better cheek weld on the stock, or to keep your head down under the flying bullets of the enemy, or to reduce the parallax between the scope and the barrel. Besides, if that were the case, lowering the rings would raise the barrel and make your groups even higher.
If you can't adjust the scope to hit dead center without coming close to bottoming out, then go ahead and use the offset inserts for the rings. That's what they're for. I would only suggest you change the rings or base if you're uncomfortable with the height of the scope as you mount the rifle,