Guy in a Garage Gets Quiet… in 5.56 and 7.62 (.300 BLK)

(Yes, 80s-90s era SF’ers, the “5.56 and 7.62” is a Blank Frank Toney reference. For the rest of you, on with the story). Our good friend Guy in a Garage (hereafter Guy) has been up to all kinds of good. You may recall that some time ago he applied to the ATF to manufacture suppressors on ATF Form 1.

He didn’t go about it by half measures. Here’s his 5.56mm suppressor, showing 3D design, computer finite element analysis of the projected flows, and parts machined, mostly, from 7075 round bar stock. The tube is Ti alloy. There’s a large chamber, followed by a blast baffle.

giag-suppressor-internal-2While the baffles are generally made of aluminum, the blast baffle is 416 stainless. Guy says:

This took a lot of work and I’m glad everything came out so well. I knew from the start that I aluminum wasn’t going to hold up to 5.56. I also knew that excessive backpressure could cause some issues in this short of a barrel. My design is based on the AAC M4-2000. It has a large expansion chamber, one blast baffle, and several clipped cones spaced closely together. This blast baffle does a lot to keep backpressure reasonable. I milled it from 416 stainless.

Here’s the 3D design of the blast baffle:giag-suppressor-part-2

The regular baffles. These are very reminiscent of some baffles Gemtech uses, as discussed below.giag-suppressor-part-3 Here’s the FEA of the baffle, showing the projected pressure drop across it. Noise suppression is all about managing pressure, temperature and time. (Software: Autodesk Flow Design, which is free as in beer).giag-suppressor-flow-sim-2

And here’s similar beauty shots of his .300 Blackout suppressor.

giag-suppressor giag-suppressor-baffle

A look in at that type of baffle. That’s not a baffle strike, that’s a feature of the design:


And here are the pair of them, completed and installed:


There are some other Guy in a Garage features there, including a home-made lower and home-made thermal sight. He used a quick-detach system designed by Yankee Hill Machine.

A suppressor (or any muzzle device) made of aluminum alloy, even a strong one like 7075, is going to have durability issues relative to one made of steel or exotic material like cobalt alloys (Inconel) or titanium alloys. But the exotic metals are much harder to machine than steel. This is one reason that selective laser sintering has been cost-effective for prototyping and limited production in such exotics. If you’re limited to subtractive manufacturing, aluminum alloys and steels are much more easily cut.

A word on baffles. We just got to try out a Walther .22 with a Gemtech suppressor that uses a similar style baffle. The suppressor was Hollywood tiny, but with subsonic ammo it was graveyard quiet. In fact, close to Hollywood quiet. (You do know the sounds of “suppressed” firearms in movies are dubbed in in post-processing by the Foley artists, right?) It made our old Hi-Standards sound like a 2″ .44 Magnum by comparison. We didn’t try the pistol with supersonic ammo, but the guy who had the Gemtech (his organization’s, we think, not personal) says it’s still extremely quiet, just not that quiet.

In the Gemtech, the little notch that looks to the novice eye like an artifact of a baffle strike — it isn’t — is turned 90º from the one in the preceding baffle. The Gemtech’s baffles are made of titanium, one reason the suppressor is as light as it is small.


We should have initially included these, in which Guy (username Flood_) answers many questions: Imgur thread and Reddit thread, both from three weeks or so ago. Don’t forget to click the “More comments” button at Reddit.

14 thoughts on “Guy in a Garage Gets Quiet… in 5.56 and 7.62 (.300 BLK)

  1. Docduracoat

    If he wants to paint those suppressors or lowers I would cerakote them with heat resistant cerakote c for free
    Any 3 color camo pattern or single color
    That bare metal is begging to colored!

  2. Aesop

    Footnotational point of order:

    The sound effects, whether of suppressed gunshots, or most anything else you hear in a movie that isn’t music soundtrack* are dubbed in after the movie is finished by the sound editor(s). Usually from a library of same, and/or their own carefully recorded personal collection of sounds, usually both, all lovingly and geekily tweaked electronically to come up with anything imaginable. Like f’rinstance wookie speech, R2D2 beeps, and light sabers cutting through the air.**

    The foley artists, OTOH, are the folks doing things like juggling broken china to simulate pottery breaking, dropping meat cleavers into cantaloupes to get just the right “Thunk!” sound of someone taking an arrow in the chest, and tiptoeing in place across squares of sand, gravel, concrete, etc. in everything from high heels to hob-nailed boots with a boom mic pointed at their feet to get just the right sort of footstep. All of which is recorded by another sound effects editor for current or future use. See above.

    In short, the editor(s) is/are the conductor(s); whereas the foley artist is to the movie’s sound as the 4th clarinet or timpanist is to the symphony.

    *(Oh, they can do the soundtrack editing too, but as a rule, with a lot less liberty and wizardry on how they alter it. That part is mainly about cues and timing with the story on the screen.)
    **(To prove to anyone that any movie is 60% sound and 40% visual, imagine a scene with the above sound moments, first as an audio only with no picture, and secondly, as visual only with no soundtrack. Which one you could follow better – in fact even only in your head, just thinking about them – without the missing part? Told ya so. This is why talkies caught on so much better than silent movies. We now return you to the fascinating exposition of a certain set of home-design silencers, already in progress.)

      1. Aesop

        Hey, the technical aspects are fascinating (and truth be told, most of the behind-the-camera craftspersons are salt-of-the-earth types, and a far more balanced spectrum of America).
        The above-the-line people (who are 97% of the budget of making the movie, BTW) – producers, directors, talent, and writers – tend to be from a higher concentration of unredeemed utter douchebaggery per capita than what exists anywhere in the world outside the District of Columbia, or any third-world Trashcanistan rightfully described as Outer Sh*tholia. But I repeat myself.) Take Obi Wan’s comments on Mos Eisley, substitute Hollywood, and you have every description of Hollywood ever penned by mortal men, including no small number of denizens of same.

        And I, in return, defer to your expertise on silencers specifically, and weaponry in general. Nice write up!

        Under the heading of Shooting Fish In A Barrel, a pending featurette for you:
        When Guns Are Outlawed, Only Outlaws Will Have Casino Party Busses.
        13 dead, 30+ injured, 6 in ICU, and all it took was one sleeping driver going 80MPH into the back of a semi trailer going 5MPH. BTW, most of the passengers were asleep, and did we mention that tour busses have no seatbelts? Yet.
        Lacking IDs, they’ll be using DNA to ID all the bodies – and parts of same – for some number of days.

          1. Aesop

            I’m sure they had ID, but not after the impact.

            75MPH homo sapiens pate’. The front twenty feet of the bus, the rear ten feet of the semi trailer, and any number of mixed people parts disappeared as they were pummeled into grisly meatloaf and scattered in a starburst pattern from the point of impact outwards.
            These were folks ranging from 20’s to 60’s riding the late night indian casino party bus back towards L.A., when suddenly everything went all ‘splodey, when their bus stopped, and the passengers all flew forward to meet the slow-moving trailer with which the (probably sound asleep, because no skid marks) driver collided. Purses, bags, and anything not in pants pockets all ended up mixed among the zombie salad.
            Pretty much the sleeping occupants of the bus’ first three seating rows were all turned into a Picasso version of their former selves in fractions of a second, as the subsequent rows of seats and the occupants of same stacked into them.

    1. robroysimmons

      I met a guy who claimed to do the breathing for the pilots in Top Gun also said he was in the studio with Kelly McGillis who it seems was doing her own breathing. It seemed like a legit story, the guy was a go getting gadfly doing a stint as a diving instructor for a commercial diving school amongst other career endeavors.

  3. DaveP

    Wondered about the ‘cutaway’ on the narrow end of the baffle; assumed it was to allow visualization of the thickness gradient of the cone milling, not an actual asymmetry of the opening.
    Offset by 90, in succession, you say?

    Cool pressure depictions.


    1. Hognose Post author

      The hole appears to be drilled (or, more probably, milled) at a 90º angle perpendicular to the long axis of the suppressor. It’s a half, or slightly-less-than-half, circle.

      The offset 90º in orientation of each baffle as viewed from the open end of the suppressor, is my observation of the little Gemtech .22 can whose performance so impressed me. I realized only later that Guy was using a different company’s baffles as his model — it’s explained in his Imgur link.

  4. 10x25mm

    Inconel superalloys are nickel-based. The only Inconel alloy with a deliberate cobalt addition is 617. Inconel 718, the superalloy most commonly used in suppressors, has a 1% maximum cobalt specification. Typical cobalt-based alloys have tradenames like Stellite, Haynes, and MarM.

    Nickel-based superalloys are strengthened by their titanium and aluminum constituents, which form nickel titanide and nickel aluminide particles during solution treatment and aging operations. Cobalt-based superalloys are strengthened by carbides during similar solution treatment and aging operations.

    Cobalt-based superalloys have greater bare surface hot gas cutting resistance due to their higher chromium content. Nickel-based superalloys are limited in their chromium contents due to their tendency to form harmful sigma phase zones. The gas turbine manufacturers boost nickel-based superalloy’s gas erosion resistance with special coatings, but these coatings probably would not endure the sharp pressure surges inside suppressors.

    Cobalt-based superalloys would be better in extreme suppressor baffle service where their superior gas cutting resistance would reduce edge erosion of bullet passages holes. Nickel-based superalloys would probably be better in suppressor tube service where their superior high temperature creep strength would reduce tube distortion during unrestrained full automatic firing.

    No one seems to like SAE J775 automotive poppet valve alloys for suppressor parts, despite a long history of cost effective service in conditions akin to suppressor service. FN has used Silcrome 1 (HNV 3) for gas system parts on their firearms going back before WW II. It is mostly used for heavy duty diesel engine intake valves – which would be a good source of prehardened alloy for baffles with just a bit of machining. 23-8N (HEV16) is the most common diesel engine exhaust valve (head only, the stems are Sil 1) alloy – which would be a yet better source of prehardened alloy for really severely torched baffles.

    A quick trip to a diesel engine rebuilding shop could provide the raw material for a bunch of cheap suppressor baffles. Diesel engine valves are usually replaced due to stem or seat wear, but their heads still have plenty of remaining service life. 23-8N is readily GTA weldable, which would allow joining HEV16 baffles to regular AISI Type 304 tube sections acting as baffle spacers.

    1. Bert

      YEEHAW!!! So much lovely (new to me) material science and general naughtiness related information in one randomly accessed post. This is going to take some research time…

      I have a job where I am usually trying to produce MAXIMUM db per fuel expense/ignition event… It is Through the Looking Glass time for me to consider the opposite intent, and the durability of devices intended for same.


    2. Dyspeptic Gunsmith

      Thank you for all that information. I shall be paying a visit to some diesel guys here in the very near future as a result.

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