Detent-delayed blowback uses a spring-loaded detent installed inside the bolt (I.E. a roll-pin) that locks itself into a notch on the end section of the guide rod closest to the barrel chamber rather than a section of the receiver/trunnion.[1][2] This can increase the capability of handling higher pressure pistol cartridges, as well as increasing accuracy and handling. Removing the detents from the bolt would turn the operation into a simple blowback operation. The Show Low Manufacturing Black-Jack pistol caliber carbine uses this operation.
