Why Merrill kept the cruisers at six-inch range

Did the cruisers enter secondary-battery range during the battle?

At points they may have, but Merrill generally kept them at effective six-inch range to exploit radar fire control and avoid Japanese torpedoes.

Some phases may have approached secondary-battery range, but that was not Merrill's preferred geometry. He sought to keep the American cruisers where their six-inch main guns and radar fire control remained effective. Maintaining that distance also reduced exposure to Japanese long-range torpedo attacks. Radar fire control helped the cruisers fight at the distance Merrill preferred.