No, katanas or any traditional swords are not designed to effectively block or deflect bullets. The speed and force of a bullet, along with the hardness and density of the materials involved, make it nearly impossible to block or redirect a bullet with a sword.

Bullets travel at extremely high velocities and have significant kinetic energy. When they impact a solid object, they can penetrate or pass through it, including metal, wood, or other materials. Swords, including katanas, are not designed to withstand or redirect the impact of bullets.

Attempting to block or deflect a bullet with a sword would likely result in the bullet penetrating the sword and potentially causing harm to the wielder.

It's important to note that firearms and bullets represent a significant advancement in warfare technology that emerged well after the time of the samurai and the development of traditional swords like the katana.

If you are concerned with personal safety or self-defense against firearms, it is advisable to explore appropriate modern self-defense measures, such as seeking shelter, utilizing cover, or, if legally permitted, employing firearms or other contemporary self-defense tools specifically designed for that purpose.

Always prioritize safety and follow the laws and regulations of your jurisdiction when considering any self-defense options.