- There are a lot of things that happen in a very, very short time during the discharge of a firearm. Knowing what is happening and why helps understand how the firearm reacts during that process.
- The operator of the firearm pulls the trigger.
- The hammer or striker impacts the primer of the ammunition round.
- The primer explodes and ignites the propellant (the gunpowder).
- The gunpowder burns rapidly, building pressure and pushing the bullet down the barrel.
- The rifling on the inside of the barrel imparts a spin on the bullet, stabilizing it during flight.
- In a revolver, bolt-action, pump action, and break action, the operator loads the ammunition rounds manually.
- In semi-automatic and automatic firearms, the action pulls a round of ammunition from the magazine or tube.
- With iron sights, the operator aligns the front sight in between the rear sights and aligns those with the target.
- With optics, the operator sights in the target.
- The operator squeezes the trigger.
- In many modern-day firearms, the trigger squeeze deactivates the transfer bar safety mechanism, which allows the hammer or striker to transfer its energy through the transfer bar to the primer.
- At the release point, the hammer or striker impacts the transfer bar, which in turn impacts the firing pin, which impacts the ammunitionís primer.
- The primer explodes.
- The primerís explosion lights the gunpowder.
- The gunpowder burns quickly. The burn rates can vary for different kinds of ammunition, based on the length of the barrel.
- As the pressure builds during the explosion, the firearmís barrel contains the explosion except for the two ends. The barrel must have enough strength to contain the explosion, which wants to expand outward in the shape of a sphere.
- The bullet is just slightly larger than the inside of the barrel. The force of the explosion forces the bullet down the barrel, which has groves that spiral down the inside.
- The barrelís groves, called rifling, cause the bullet to start spinning along its trajectory axis, like a football thrown by an experienced quarterback. That spiraling causes the bullet to fly straight.
- The force of the explosion also pushes back toward the other end of the barrel.
- In a semi-automatic firearm, a small part of that force is used to cycle the firearm and prepare the next round to fire.
- The operator feels the force as perceived recoil.