Výhradně dvojčinná spoušť

Double Action Only (DAO)
It is a type of trigger and percussion device for a small arms. It is sometimes also called a "two-function trigger only" or a "trigger tension". Both names ( double-acting or double-acting) refer to the fact that by pressing the trigger the trigger device performs two functions in succession - first the drum mechanism is tensioned, and then it is released, which ensures firing. bullets.


The word "only" in the name of this mechanism draws attention to the fact that this type of device cannot be pulled other than by pressing the trigger. It is therefore not possible to tension the cock to the rear position, for example with the thumb or the movement of the breech, and after the shot, the drum device always returns to the initial position.


Its tension is therefore always repeated only by a continuous pressure on the trigger, which ensures that the striker or hammer is pulled to the rear position and released when the mechanism reaches a critical point where its components come out of engagement ( also ensures the rotation of the cylinder).


The advantage of triggering in exclusively double-acting mode is higher firing speed compared to a single-acting device, but the disadvantage is a much longer trigger step and its several times greater resistance, which significantly reduces the accuracy of shooting and hitting the target requires training.


Historically, it is the second type of trigger and percussion system for small arms (after single-acting), patented in 1837 by Ethan Allen. Today, it is often used in small defensive revolvers, where it is intended to be used directly from the pocket ( and where the movement of the cock could be blocked by a substance or the thumb's thumb could catch on it during drawing) and where in addition, accuracy is irrelevant when shooting at short distances.


It is also a very common solution ( including a variant with partially prestressed direct-running striker) for modern pistols, as it is a safe system that allows you to carry a pistol with ammunition in the chamber, which also shows the same trigger characteristics ( stride length and resistance) compared to double-acting trigger.


Sources:
A. E. Hartink: Encyclopedia of Pistols and Revolvers, ed. Rebo productions, s. R. O., Prague 1997, ISBN 80-85815-66-4
F. Novotný, A. Kreml, M. Helebrant: Weapons and Self-Defense, ed. Goldstein & Goldstein, Prague 1997, ISBN 80-86094-23-5
Zdeněk Faktor: Weapons for self-defense, published by Magnet-Press, Prague 1995, ISBN 80-85434-76-8
URL : https://www.valka.cz/Vyhradne-dvojcinna-spoust-t212778#645541 Version : 0
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