A cast iron skillet is not designed or intended to be used as a bulletproof material, and it would not reliably stop a bullet. While cast iron is a sturdy and dense material, it is not designed to withstand the extreme forces and velocities associated with bullets.
Firearms can propel bullets at high speeds, and when a bullet impacts a dense material like cast iron, it can easily penetrate through it. The skillet would likely fracture, shatter, or deform upon impact, and the bullet would continue to travel through it.
For personal protection against bullets, it's essential to rely on appropriate bulletproof materials and equipment designed and tested for that specific purpose, such as body armor made with bullet-resistant materials like Kevlar or ceramic plates. Always prioritize safety and use proper protective gear in potentially dangerous situations.