Monolithic bullets do not have a jacket, they are a solid block of metal, typically copper. They are often preferred by hunters over copper-jacketed bullets for many reasons. Firstly, they are a more environmentally friendly alternative to the toxic lead bullet, but more so, the bullet does not break apart like the softer lead bullet which causes meat damage. The monolithic bullet also retains its size and shape far better, which allows for deeper penetration allowing the bullet to reach vital organs in large game while delivering more kinetic energy to disrupt them. Due to the precision manufacturing process, these bullets achieve high accuracies, with flat trajetories and reduced drag. On the downside, they are expensive and decrease barrel life.
