SILENCER SATURDAY #86: Hush Puppy Project Slide Lock And System

    Hush Puppy

    Good morning everyone and thank you for joining us for the 86th edition of Silencer Saturday. Last week we laid out some basic tips and advice for new silencer owners, prospective buyers and anyone else who gets their firearm information from mainstream media and Hollywood movies. Today, at the other end of the spectrum, we’ll be getting a preview of a more advanced silencer system that should arrive at TFB HQ in a few weeks. The Hush Puppy Project is a Louisiana-based company that built it’s recently patented technology from Vietnam War era setups used by U.S. Navy SEALs/UDTs.

    SILENCER SATURDAY #86: Hush Puppy Project Slide Lock And System

    We’ve discussed, at length, the sources of noise from semiautomatic firearms. Besides the obvious muzzle report, the chamber opening and ejecting a spent casing round can also be an issue depending upon the type of action of the host weapon. The majority of modern pistols operate on a tilting barrel design, some of which can be decent hosts for silencer use, some of which are less than optimal. The only way to make completely sure you are maximizing your suppression is to stop the action from opening and prevent the gas from venting near the shooter. A single shot, yet quiet, setup for discreet use.

    Enter the Hush Puppy Project. By inventing a slide lock for semiautomatic pistols (currently the GLOCK G19 and the S&W M&P 2.0) the host firearm is converted into a single shot host for maximum suppression performance.

    Hush puppy

    GLOCK Silde Lock – Hush Puppy Project

    The modified GLOCK or S&W is one part of a system that includes one of two models of silencers and 158gr  or 147gr Super Vel subsonic 9mm ammunition. The Hush Puppy Slide Lock design recently received a patent approval.

    Hush Puppy

    Hush puppy

    Hush Puppy

    Hush Puppy Project

    Slide Lock Patent Granted To Hush Puppy Project LLC

    On August 13, 2019, The U.S. Patent Office granted US Patent No. 10,378,838 to the Hush Puppy Project for its Slide Lock Device (“SLD”). Hush Puppy Project is a Louisiana-based manufacturer of suppressors, pistols and ammunition “dedicated to the art and science of small arms signature reduction.

    US Patent No. 10,378,838 is directed to a mechanism that converts a semiautomatic pistol’s self-loading system to a single-shot locked breech mechanism, thus eliminating the mechanical sound of the slide cycling, the emission of noise from the ejection port (“port pop”) and collateral sound from brass hitting the ground while allowing the suppressor to achieve maximum efficiency.  With the SLD disengaged, the pistol may still be fired in normal semiautomatic mode.

    “Our new SLD patent covers the mechanism thatconverts a Glock pistol to function in locked breech mode, thus making for the quietest shot possible, especially when combined with the Hush Puppy Model 2 wipe silencer and Super Vel Mk 144 subsonic ammunition.” said Brad Gilpin, Hush Puppy Project president.

    The Hush Puppy Project currently manufactures two brands of pistols with SLDs, Glock 19 Gen 5 and S&W M&P 2.0 as well as two suppressors, the Model 1 and Model 2. Super Vel Ammunition, a sister company of the Hush Puppy Project, manufactures subsonic 9mm ammunition as part of the Project’s “systems approach” to sound reduction.

    Hush Puppy Project guns, suppressors and ammunition are available exclusively from Lipsey’s, a firearms wholesaler servicing stocking gun dealers. Military and Law Enforcement customers are manufacturer direct. The Hush Puppy Project is located in Baton Rouge, La.

    The MK 22 “Hush Puppy” – A Vietnam-Era UDT weapon system.

    The original Hush Puppy was a S&W Model 39 with a slide lock and was designated the MK 22 (and MK 23 pistol and silencer kit).


    The original Hush Puppy was a modified Smith & Wesson Model 39 with a slide lock. The MK 22, used by Navy SEALs or UDTs during the Vietnam War was also part of a system including a silencer and subsonic ammunition. It appears that the pistol was referred to as the MK 22 whereas the whole kit was referred to as the MK23 Mod 0 – not to be confused with the stealthy .45ACP MK 23 pistol from Heckler & Koch.

    The following information about the original Mk 22 Hush Puppy was taken from NAVSEA OP 3703 Volume 5 Part 4, Preliminary Technical Manual, Swimmer Weapon System, Guerrilla And Covert Warfare, Department of the Navy.

    Mk 22 Hush Puppy:

    9mm Pistol Mk 22 Mod 0 is designed for use with 9mm Pistol Noise Suppressor Mk 3 Mod 0. The noise suppressor attenuates muzzle blast and eliminates muzzle flash. The pistol has a slide lock which substantially reduces the mechanical noise of the pistol’s action and eliminates chamber flash. With the suppressor attached and the slide locked, the pistol is essentially inaudible. The use of sub-sonic 9mm ammunition is required for maximum reduction of blast, but standard service issue 9mm ball ammunition
    may be used if a significantly higher sound level is acceptable.

    The MK 22 Pistol:

    The 9mm Pistol Mk 22 Mod 0, a modified S&W Model 39, is a double action auto-loading pistol of 9mm Parabellum caliber with a magazine capacity of eight rounds. Modifications to the Model 39 include the addition of a slide lock, the incorporation of higher sights to allow sighting over the suppressor, use of a longer threaded barrel to accommodate the suppressor, minor action modifications, and replacement of the wooden stocks with plastic. The internal springs are corrosion resistant steel. All external parts of the pistol have a black matte finish.

    The Slide Lock:

    The side locking lever assembly provides a lever on either side of the slide secured by a single pin which passes through the frame. The levers engage notches in both sides of the slide, locking the slide in place. This prevents the mechanical noise of the slide as well as preventing sound or flash from escaping from the chamber. Use of the slide lock prohibits semi-automatic firing.

    The Barrel:

    The six groove right-hand barrel is five inches long, one inch longer than the Model 39 barrel. The extra length extends beyond the slide and is threaded to accomodate the suppressor. The threads are 1/2″ – 32.

    The 9MM Noise Suppressor MK 3 MOD 0:

    The noise suppressor, Figure 2-1, comprises a black anodized cylindrical aluminum tube closed at both ends by threaded end caps and a replaceable suppressor cartridge assembly. The suppressor cartridge is held in position by the front end cap and a retainer spring assembly. The suppressor cartridge is a retainer spring assembly. The suppressor cartridge is a sealed aluminum cylinder which contains for soft plastic discs 1/4-inch thick which are spaced along the longitudinal axis of the cartridge with air gaps between them. The end caps have 1/2-inch holes centered on the long axis of the noise suppressor. The back end cap has a threaded collar to allow the device to be screwed onto the muzzle of the pistol barrel. When separate from the pistol, the back end cap is plugged with a removable back end cap collar, on both end caps, and at the mating surface between the front end cap and the suppressor cartridge.
    The following images and information are credited to Kevin Dockery, author of Weapons Of The Navy SEALs and Special Weapons, Special Warfare.
    Hush puppy

    Credit: Kevin Dockery, author of Weapons Of The Navy SEALs

    Hush Puppy

    Kevin Dockery, author of Weapons Of The Navy SEALs

    Hush puppy

    Kevin Dockery, author of Weapons Of The Navy SEALs

    Hush Puppy Project – Pistols

    Fast forward 50+ years and you can now own a modern-day complete Hush Puppy system. Modified pistols and complete silencers are available for dealer order through Lipsey’s.

    Hush Puppy Project – Silencer

    The Model 1 is a modular silencer that achieves a unique hybrid design consisting of monocore and wipe sections.  The Model 1 is different than everything else on the market and requires specific techniques and procedures to enjoy maximum signature reduction.  We call this ability to utilize different modules and wipes, with or without an ablative agent, “Tunable Technology.”  Tunable Technology offers the Model 1 owner the ability to control the length, weight, tone and level of sound suppression from a Model 1 silencer.

    • Model 2 – Price TBD

    The Model 2 is a wipe-based silencer design intended for maximum sound reduction in a silencer of minimal size. The Model 2 is novel, but shares the same basic technology— the use of wipes to reduce sound— as the Nam-era, SEAL-issue suppressor called the Mk 3 (which was a companion to the SEAL’s Mk 22 Mod 0 “Hush Puppy” pistol). The Model 2 utilizes six wipes which are replaceable by the user when the wipes are damaged from normal use (becoming less effective as the bullet and powder gases create a larger and larger exit hole). The Model 2 is also a modular design in that it comes with a second module containing additional wipes to replace damaged wipes or to be affixed into a solid unit (both modules together) for greater sound reduction, but at the expense of compromising the Model 2’s compact size.

    Hush Puppy Project – Super Vel Subsonic Ammunition

    In 1967, the U.S. Navy type-classified Super Vel’s 9mm subsonic 158 gr. FMJ as the Mk 144 Mod 0 ammunition, designed for their Mk 22 Mod 0 “Hush Puppy” pistol. We have duplicated the ballistics with the same bullet at the Navy’s specified 965 fps velocity. This load was necessary to replicate the recoil impluse of standard 9mm ball so that even with a suppressor attached, the Mk 22 pistol would still cycle reliably. The 158 gr. Hush Puppy load is specifically made to cycle suppressed pistols with the original factory recoil spring whereas our similar 147 gr. subsonic load may require a reduced-power recoil spring to cycle with a suppressor.

    For a full performance review, we’ll need to wait a few weeks for the modern MK 22 to make its way to Silencer Saturday. Stay tuned.

    Have fun, be safe and we’ll see you next weekend for TFB’s Silencer Saturday.

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    Editor In Chief- TFB
    LE – Silencers – Science
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