Breech

A breech (also called a bolt) is an internal component found on breech-loaded blasters as well as most clip system Nerf blasters.

Details
A bolt consists of two parts: The breech itself and the breech sled. The breech sled moves the bolt and is attached to the priming mechanism. When the blaster is primed back and forth, the bolt grabs a dart from the clip, when it reaches the end of its cycle, a dart tooth helps push the dart all the way down on the dart post in the breech.

Breech-loading
In breech-loading blasters like the IonFire, the breech is placed upside down, so that when the breech is opened, it can allow the user to place in a dart.

Modification
Some modders remove the air restrictor from the bolt, and add brass into the breech. This helps air flow and increases performance.