HS 21 PTB 22 – Small holes in cylinder chambers

There is 1 reply in this Thread which has previously been viewed 172 times. The latest Post (July 7, 2025 at 7:28 AM) was by Gabor VASS.

    • New

    Hello everyone,
    I recently acquired a HS Modell 21 revolver in 4mm R Lang with PTB 22 markings and the "F-in-pentagon" free weapon proof. I noticed something unusual that I hope someone here can help explain.

    Each chamber in the cylinder has a small round hole drilled inside a longitudinal groove (not the large lateral gas relief ports, but tiny pinholes visible near the chamber walls). These look precise and factory-made. Are these original features from the factory or do they serve a specific purpose for PTB compliance (e.g., gas pressure regulation or anti-conversion measures). Has anyone seen official documentation, blueprints, or a technical PTB description related to these holes?

    Any help would be appreciated! I'm trying to learn more about how these revolvers were constructed and approved in Germany.

    Thanks in advance for your insights. :)

    • New

    This is NOT a gas-alarm gun (PTB in Circle), but an under-7,5J indoor training pistol (also called "flobert gun").

    As the 4 mm Rimfire Long is ABOVE the 7,5 J limit (cca. 15-25 J), these holes are needed to reduce the muzzle energy under 7,5 J.


    The PTB in Square is the homologization symbol/mark of it in Germany.


    (I think you are from Czechia, so you do not need this limitation, as the C-1 category floberts do not have to be under 7,5 J.)