Would a 20-inch naval shell need explosives?

The battle pauses for a question about whether a hypothetical 20-inch shell would need an explosive filling at all. At that scale, a solid steel projectile might rely on mass and impact for its destructive effect. The point is exploratory rather than a settled engineering judgment, and the passage includes no calculation of penetration or terminal effects. A chat suggestion about seawater in railgun projectiles is acknowledged only as an interesting comparison, so it does not demonstrate a historical weapon practice.