Why some 4.5-inch shells carried spiral grooves

Why did some 4.5-inch naval shells have spiral grooves near the nose?

It is associated with maintaining spin and accuracy, with lighter and heavier projectiles using related features for differing ballistic purposes.

The proposed explanation connects the spiral feature with maintaining spin and accuracy. The assumed examples are wartime 4.5-inch shells, with lighter projectiles facing stabilization problems and heavier examples using a related feature for a different purpose. Stabilization and accuracy are treated as separate applications. No particular shell model is identified, so the explanation should remain tied to the described feature rather than every 4.5-inch projectile.