hk slap
A method of releasing the charging handle from the notch of a firearm, particular ones located at the front of the weapon. This action is mainly done on firearms featuring a roller delayed blowback system, since the roller requires the bolt to travel forward with some force to properly lock.
The action is mainly associated with Heckler & Koch firearms, including the MP5, the G3, and the UMP, as the manufacturer recommends this action in its operator manuals.