Blast‐induced traumatic brain injury caused by road bombs has lately become a larger part of allied injuries. The same mechanisms may also be responsible for milder injuries of similar nature, resulting from training with large caliber weapons and explosives. In this paper, the blast effects from a weapon on the brain are investigated. Using the hydrocode AUTODYN, numerical simulations of shock wave propagation into the brain are performed. The shock wave is calculated from a complete numerical simulation of the weapon, including the burning gun powder gas inside the barrel, acceleration of the projectile, and the rapid gas flow out of the muzzle. An idealized head is placed in the simulation at the position of personnel firing the weapon. Here we focus on the qualitative mechanisms of the propagation of the shock wave through the skull and into the brain. The results are compared with experiments carried out on anesthetized animals. To simulate real training scenarios, pigs were placed in position of personnel and exposed to impulse noise generated from weapons. Blast parameters in the air were correlated with those in the brain.