the locking jaws 48 and 49 are displaceable between a locked and an unlocked position via an eccentric means not shown and a locking mechanism 6 by means of a key not shown in a manner similar to that illustrated with respect to the embodiments above a locking tongue 31 is provided in the upper part of the locking device 1 said locking tongue in the locked inserted position preventing the rear edge 47 of the barrel 29 from being displaced downwards a part of the upper plane 45 of the barrel 29 thus remaining in engagement with the ejector opening 46 preventing casing movements whereby the means that in the pistol 43 corresponds to the bolt is locked indirectly and unauthorized dismantling of the barrel 29 and the bolt cannot be made without damaging the locking device 1 or the pistol 43 also this embodiment may be provided with an engagement catch means not shown in addition the body 2 is also in this embodiment manufactured from a hard material preferably hardened steel in order to make damage or violation of the locking device 1 more difficult it is particularly preferable to manufacture the body 2 from a deep hardened block of e g steel it is likewise preferable that for instance the various locking jaws are manufactured from a hard material such as hardened and particularly deep hardened steel just like in accordance with the embodiment above the locking unit 5 is enclosed also in this embodiment by the magazine guide 4 which in this case corresponds to the pistol grip in addition also in this embodiment.