9 mm Mark 22 Mod. 0 Pistol Chamber Plugs

Hi everybody,

 I need a correct scanned image of both variations of the 9 mm Mark 22 Mod. 0 Pistol Chamber Plugs (black and white complete with O-Ring).

 Thank you very much.

Fede - the scan has been sent to you from my own email. I will have Joe post it here as well, to complete the thread.

Hope it is o.k. Best I could do. The white one posed problems. When it looked best, the black one was nothing but a black silhouette.

These are the 9mm Mark 22 Model O Chamber Plugs from the smith & Wesson Hush-puppy System.

John Moss

What are these used for?

I’m sure someone else will chime in with the details, but it’s my understanding that these chamber plugs were used in the silenced S&W M39 “Hush-Puppy” pistols used by Navy SEALs; since they were most often delivered by boat, quite often swimming ashore, they needed some way of keeping water out of the pistol’s barrel and suppressor, and these plugs were developed as a way of helping to do that. Am I that far off, from those who have a more complete story?

SDC, thanks! So there was also plug for the silencer muzzle I guess then?

In the British Army they’d have used Black Masking Tape at both ends and wondered why water had got in :-)

Just pour the water out afterwards. I have done it many times. Its alright with a 9mm but don’t let it happen with anything like a 7.62 or 5.56.

In the British Army they used to put condoms over the barrels of the SLR. I don’t know if they still do it with the SA80. It was the source of many (rather predictable) jokes.

I believe so, but the muzzle end would have likely either been sealed with tape or a cork, or a replaceable “shoot-through” front baffle in the suppressor.

The ammunition for this pistol was packed with four chamber plugs, a group of white plastic muzzle-plug discs, a barrel cap and a back-end cap plug. I believe the latter two were for the silencer if it was carried under water detached from the pistol. I do not know why some chamber plugs were white and some were black.

If the pistol was carried “ready to use” under water, the muzzle disc was applied to the silencer and was designed to be shot through. The chamber plugs were carried in the chamber of the pistol. All that was necessary for immediate use once out of the water was to rack the slide to eject the chamber plug and load a 9mm Mark 144 Model O live cartridge. There were 24 rounds in the box. There was also a spare suppressor insert in the box, that being “the heart of the suppressor,” containing the plastic inserts (baffles) that actually reduce the sound. They were designed to be shot through, and evidently as more shots were fired, the sound got louder, as with many silencers. the life of the insert was considered the 24 rounds in the box.

The Mark 144 round was a special, subsonic cartridge loaded with a 158 grain bullet and identified by a green bullet tip. It had a nominal muzzle velocity of 965fps.

The whole system was mounted on a highly-modified Smith and Wesson Model 39 self-loading pistol. The slide stop would actually lock the slide shut during firing if desired, thereby reducing or eliminating the residual sound signature at the ejection port. The first version of the pistol was a bit different than the Mark 22, and evidently was simply referred to by the basic commercial designation of Model 39, or as “Modified 9mm Autoloading Pistol.”

Only about 100 to 120 of these pistols were made, specifically for U.S. Navy UDT and SEALS Teams. For a more complete account, see the reference below. The reference is in agreement with the unclassified pages of the manual for this pistol system, as far as I can tell from a cursory examination.

Reference: The Small Arms Review, Voume 5 No. 9, June 2002, pages 68-69.

Great scans John!!!

                           Thank you very much. 

Can anyone give a description of the cartridges that were used in the Hush-puppy system? In “The Cartridge Trader”, December 1975, Bob Leiendecker describes one 116 grains FMJ identified with a black case or black tip and the Mk 144, 158 grains FMJ with a green tip.

I have three rounds which I have thought to be Hush-puppy rounds:

All headstamps are “SUPER VEL 9MM LUGER” and the one in the middle has a three-stab crimped primer. They are all the same weight, 223-225 grains, which make me believe they all are loaded with a 158 grains bullet.

Is my identification correct?


John is correct. I believe the black and white come with the Silencer kits. I have two additional US chamber plugs. One is brown and has a much wider groove and the other is black aluminum with a flat tip. I believe this is a more current version of the plugs.

Lew - good add, my friend! I have never seen either of those other types of plugs, and to quote a line from my favorite movie, Tombstone, “Hell, I ain’t never even heard of it.”

Thanks for posting that.

Morten, I think the three supervel rounds you picture are Hush-puppy loads. The loads which come with the silencers and the chamber plugs are the IVI headstamped loads with green and black bullets. My boxes for these rounds came empty so I cannot tell ou whether they were green or black bullets or whether the chamber plugs were black or white. One of these box came with a plug and ammo to the guy I got it form, but he emptied it and I don’t have a note on what was in it.

Cheers, Lew