Build Your Own Silencer – Part 1

PART1

Don’t look at me like that. Yes, it’s perfectly legal to build your own suppressor. Following the same process as you would to make a registered and legal short barreled rifle (SBR) or short barreled shotgun (SBS), you can build a device that will make your favorite gun quieter, have some fun and even learn a few things along the way. Still with me? Great. Let’s get started.

Part 1:

  1. Introduction
  2. Maker vs Manufacturer
  3. Disclaimers
  4. Legal Requirements
  5. Basics
  6. Materials
  7. Basic Tools
  8. Homework

Part 2:

  1. Types/Designs
  2. Calibers
  3. ATF Form 5320.1 (Form 1)
  4. Paper vs EFile
  5. Resources
  6. Part Suppliers
  7. While You Wait
  8. Homework

Part 3:

  1. Approval
  2. Building/Machining
  3. Working With Metal
  4. Bore Diameter and Concentricity
  5. Baffle Clipping/Mouse Holes
  6. Mounting/Testing
  7. Coating/Painting
  8. Final Thoughts

1.1 Introduction

Commercial suppressor manufacturers have been conjuring up some awesome products in the last few years. Modern designs, materials and manufacturing processes have given buyers enough market variety to suppress almost any gun in their safe.

So why would you want to build your own silencer? For the most part, homemade suppressors can be made for a fraction of the cost of their commercial cousins. For example, my combination titanium, steel and aluminum 9mm suppressor cost about $150 (not including a booster). And my full titanium 5.56mm build cost about $350.

In addition, you can use your choice of materials, specific dimensions and custom designs to build a can that matches your needs precisely. It’s also just good clean fun: by building your owner suppressor you get a better understanding behind the engineering that goes into the products made by the big companies. Suppressing firearms is both a science and an art. Ok, it’s mostly science.

If you are not a suppressor owner yet, I highly suggest that your first (and probably second) purchase come from a commercial manufacturer rather than attempting to make one on your own. Even if you are an expert machinist, I believe your first venture into the world of silencers should be store bought. Why? Because if something doesn’t turn out right – it’s loud, or it doesn’t thread on properly, or it’s super heavy – you risk being soured on suppressors forever. And nobody wants that. In addition, commercial offerings are backed by a warranty; if something is out of spec, just send it to back and get it fixed.

Hopefully you had the chance to read through the ‘Beginner’s Guide to Suppressors’ series here at TFB. If not, I suggest that you at least read through Part 1 that covers some basic information including the National Firearms Act (NFA) legality in your area, suppressor terminology and host (gun) basics. Most of that starter information will not be repeated here in the ‘build your own’ series.

4kit

Titanium parts.

1.2 Maker vs Manufacturer

As an individual or entity (Trust or LLC) suppressor builder (also known as ‘Form 1’ builders), you are known as a ‘Maker’. While on the other hand, the Bureau of Alcohol Tobacco and Firearms (BATFE) classifies Federal Firearms Licensee/Special Occupational Tax holders (FFL/SOTs) as ‘Manufacturers’. Whereas manufacturers are in business to design, build, test and sell NFA items like suppressors, makers are approved to build suppressors for non-commercial (or resale) use only.

What this means for you:

  • As a maker, you are not allowed to build a suppressor for sale. That doesn’t mean that you can’t sell a suppressor you build down the road (you won’t), but the intent is that you are building one just for personal (or entity) use only.
  • Manufacturers are allowed to apply for BATFE variances to certain rules and regulations in the design and build process. For example, a suppressor company can petition the BATFE for a variance for a design that pushes the legal limits that define silencers – extra parts, modularity, etc. Makers, on the other hand, must follow all BATFE rules and regulations as written.
  • As a maker, you cannot ‘test’ or ‘prototype’ your designs like a manufacturer may be allowed to do. Your approved BATFE Form 5320.1 “Form 1” allows you to build one suppressor as described. More on this topic later in the series.
  • Manufacturers are allowed to repair damaged or worn suppressors with certain restrictions. Makers are not allowed to repair suppressors, even one’s they built themselves. There is some debate on this front, but we will tackle that discussion in Part 3.

A freshly drilled titanium baffle I made for a 5.56mm Form 1 suppressor.

1.3 Disclaimers

I know we are all responsible, levelheaded and lawful firearm owners, but since we will be venturing into the highly niche area of building a suppressor lawfully, here are a few words of caution:

  • I am not a machinist, master craftsman, CNC operator or blacksmith. This guide is meant for the amateur hobbyist with a basic knowledge of tools and metalworking. Know your skills and limitations in the shop.
  • I am not an attorney. And this guide isn’t meant to be legal advice. When in doubt, do your own research and contact the BATFE for clarification.
  • You are responsible for following all safety precautions. This applies to when you handle firearms as well as the tools in your garage. And don’t forget the ear and eye protection.

1.4 Legal Requirements

As discussed in the Beginner’s Guide, check the local, state and federal laws before starting down the path towards a homemade suppressor.

We mentioned the BATFE Form 1 above, and we are going to go into more detail in this part as well as the following parts. To put it simply: You need an approved Form 1 before you can start building your suppressor. Do not attempt to machine parts, drill holes or otherwise do anything that would be construed as building an unregistered suppressor.

That being said, you can purchase the parts necessary to build you silencer while you wait for your Form 1 to be approved. After all, the majority of these parts are commercially available at metal supply sources, auto parts stores, hardware stores or directly from a machine shop.

The key here is intent and common sense. Buying metal tubes is one thing; forming baffle cones and drilling bore holes is something completely different. For the most part, if your parts can be threaded onto a barrel and can suppress the sound of a fired shot, it’s a silencer and needs an approved Form 1. When in doubt, wait for your Form 1 to come back approved from the BATFE.

For your own good, and the betterment of shooters, collectors, hobbyists and builders everywhere, do not attempt to push the boundaries of the law, no matter how slight.

I am not trying to make anyone nervous, but a healthy amount of caution is ok when building NFA regulated items.

On the plus side, you don’t need to have your entire build planned out prior to filing your Form 1. Besides your individual or entity information, the BATFE only needs the caliber of your silencer and it’s overall length. A basic design or sketch is not required, but could help keep your form out of “Pending Research” – a period of time after the submission of your Form 1 where the BATFE reviews the details of your proposed build and decides whether or not they need further information prior to processing and approval.

Don’t worry, we are going to guide you the entire Form 1 process in Part 2.

image

Before: My 1.5″ titanium tube with baffles formed from steel freeze plugs and an aluminum end cap. This is a short freeze plug build for a 9mm pistol.

 

3freeze

After: My 1.5″ titanium tube with baffles formed from steel freeze plugs and an aluminum end cap. This is a short freeze plug build for a 9mm pistol.

1.5 Basics

Similar to when buying a commercial suppressor, throughout the build process it is very important to keep your needs, wants and expectations in mind. Be realistic with your goals and your budget. Here are a few things to watch out for:

  • Costs: Especially when it comes to rimfire projects, it is easy to get close to the price of a well-built commercial can.
  • Weight: There can be a tendency to overbuild your suppressor out of an abundance of caution. Just keep in mind that all those materials on the end of your barrel will add up fast.
  • Length: Similar to weight, many builders can attempt to make a silencer too long in the hopes of a further reduction in noise. Stick to ‘normal’ sizes and lengths this time.
  • Baffles/Monocore: There will be a temptation to get creative with your silencer’s internals. Remember, since you are a maker and not a manufacturer, you are not allowed to prototype and test different designs along the way. For your first build, stay with a proven, easy to make design.

1.6 Materials

2metal

Titanium scrap I picked up from eBay. After approval all of this turns into a 7″ x 2″ OD direct-thread 5.56 suppressor.

Here’s where we start getting down to business – picking out the materials you need to start your build. But before we get down to actual parts and suppliers, lets talk about the metals that can be used to build suppressors.

  • Aluminum: A lightweight metal that is easy to machine, aluminum is typically only used on rimfire builds or some pistol builds with caution.
  • Stainless Steel: Strong but heavy, stainless steel can be used on almost any type of host. Because of the weight limitations, stainless steel builds on the end of long rifle barrels should be avoided.
  • Titanium: Similar in weight to aluminum but with comparable strength to steel, titanium is an excellent choice for suppressor building. The downsides here are cost (about five times the cost of comparable steel) and machinability – low drilling speeds, cutting oil and temperature management.
  • Carbon fiber and plastics builds are (somewhat) possible but should be considered advanced builds and outside the bounds of this guide.

It is important to note that these materials can be used in combination with each other. For example, for a pistol suppressor you could use a titanium tube with steel or stainless steel baffles.

Proper planning is key. You don't have to be a mechanical engineer, but simple sketches go a long way.

Proper planning is key. You don’t have to be a mechanical engineer, but simple sketches go a long way.

Writers Note: Ok, here’s something I neglected to mention in the beginner’s guide. The tube (where the manufacturer/makers engraving is usually located) of the silencer is considered to be irreplaceable. Meaning that in the highly unlikely event of a catastrophic failure, the tube cannot be replaced, even by a licensed manufacturer. The tube can be shortened to affect a repair, but it cannot be lengthened or completely replaced (without paying another $200 transfer tax and waiting for a Form 4 to get approved).

Knowing this fact, as a maker, my suggestion is to use the best material, proper thickness and machining possible. This build needs to last a lifetime (or more). However, if damaged, end-caps, adapters and internals can all be replaced by a licensed manufacturer. All without having to pay another $200.

In fact, keep this in the back of your mind: If you somehow manage to make the worst silencer ever produced (it actually makes your gun louder) you can send it off to one of a few different manufacturers who will re-core (gut and replace) your silencers baffles and caps without having to pay another $200 tax and wait six months for approval.

1.7 Basic Tools

8endmill

An end mill I picked up from Amazon for about $20. Regular drill bits will work, but an end mill will last longer, especially when cutting titanium.

I am not going to suggest that anyone needs to run out and buy a lathe or that you need to have a garage full of the best tools money can buy. However, you do need some basic equipment to build your own suppressor.

  • Drill: A good rechargeable or plugin drill is a must. A drill press is better.
  • Drill bits: Get a new set of bits that are suitable for metalwork.
  • Hacksaw: For trimming spacer material. A Dremel will also work
  • Files: Round, flat and triangular for clipping baffles and evening out spacers. Grinders and a belt sander are nice to have.
  • Heavy duty vice: I’ll be honest, if you are forming your own baffle cones, a hydraulic shop press really is preferred. But with the right shop vice, it can be done. Plans for building your own press out of 2×4’s and using the hydraulic jack from your car can be found here.
  • Sandpaper: Smoothing and polishing.
  • Cutting oil: For drilling an cutting titanium.
7drilling

I’m drilling a bore in a titanium baffle using an end mill and dark cutting oil.

1.8 Homework

We are going to start the next part off by talking about silencer design basics, caliber ratings and submitting your BATFE Form 1.

First, decide the host that your project will eventually live on and make sure it’s suitable to be suppressed.

Second, take some time to do a little research on your own. Googling ‘suppressor baffles’ will give you thousands of pictures to look through.

Hint: For your first build, you’ll be buying a pre-made tube, a threaded barrel adapter, end cap and baffle materials like freeze plugs or Valve Stem Retainers (VSR).

Lastly, download and familiarize yourself with the information needed for the BATFE Form 1. We’ll be filling that out in Part 2.

Glossary:

  • Baffle – The cone-like sections inside the suppressor that work to slow and cool gasses.
  • Baffle Stack – All of a suppressor’s baffles together acting as one sound-reducing system.
  • Baffle Strike – When a bullet damages a silencer’s baffle.
  • Blowback – Gases that would have normally exited the muzzle are redirect back through the barrel towards the shooter.
  • Booster or Nielsen Device – An inertia device that uses the force of the trapped gases in the silencer to cycle the action of a semiautomatic pistol.
  • Bore Hole – The hole in the baffles and end cap where the bullet passes through.
  • Clipping  – Openings encompassing part of the bore hole in baffles to aid in the creation of turbulence and increasing suppression. (also see ‘mouse holes’)
  • Concentric – The process of ensuring that the entire suppressor is centered around the boreline of the barrel and barrel threading.
  • Direct Thread – A type of suppressor that mounts directly on to a barrel without the need for a mount or adapter.
  • End Cap – The muzzle end of the silencer.
  • End Cap Strike – When a bullet damages a silencer’s end cap.
  • Engraving – The maker, model number, maker location, caliber and serial number engraved on the main part of a suppressor as required by law.
  • Form 1 – BATFE Form 5320.1 an Application to Make and Register a Firearm. An approved Form 1 is required to build a suppressor.
  • Freeze Plug: Normally found in auto parts stores, theses inexpensive steel cups are made to be used in car engine blocks. They also can be drilled an pressed into Form 1 suppressor baffles.
  • Inner Diameter (ID) – The inner diameter of a suppressor tube.
  • Markings –The maker, model number, maker location, caliber and serial number engraved on the main part of a suppressor as required by law. (see engraving)
  • Monocore – A type of one-piece baffle structure found inside some types of suppressors.
  • Mount – The part of the suppressor that attached to the barrel of your gun.
  • Mouse Holes – Semi-Circle holes encompassing part of the bore hole in baffles to aid in the creation of turbulence and increasing suppression. (also see ‘clipping’)
  • Outer Diameter (OD) – The outer diameter of a suppressor tube.
  • Over-The-Barrel – A type of silencer that uses proprietary mounts that starts before the muzzle of the barrel to increase a silencer’s volume.
  • Spacer – The a section of metal that slips into your tube to create space between baffles.
  • Thread pitch – A variety of different thread patterns on the muzzle of a barrel that are usually specific to a caliber.
  • Tube – The body of the silencer.
  • Valve Stem Retainers (VSR) – Made of steel or titanium these stepped-cones are made to retain valve stems in car engines. They also make great baffles in Form 1 suppressors.
  • Volume – The amount of space inside a silencer that is available for gases to be trapped, slowed and cooled.
9form1vsform4

My Form 1 “Tank” eats my commercial can (SilencerCo Saker762).

See you for Part 2 of ‘Build Your Own Silencer’.



Pete

LE – Science – OSINT.
On a mission to make all of my guns as quiet as possible.
Pete.M@staff.thefirearmblog.com


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  • Sorry all–lately Word Press has been blocking comments I have no idea why. I’ve moved the post so you can now comment. Apologies.

    • Austin

      And as with so many tech things, I works after you restart it

    • Pete – TFB Writer

      Thanks Phil!

    • wetcorps

      I bet the ATF is behing this 🙂

      • Steven L

        I bet the press is behind it

  • Gary Kirk

    Very interesting post, will definitely be following this series closely..

    • Gary Kirk

      And good point on the valve spring retainers.. I’ve often wondered if they’d work in this regard

  • d_grey

    Very informative!

  • KestrelBike

    I’ve always found it mind boggling that one can’t make their own repairs, or do R&D on a single stamp. As long as there is a stamp and only one possibly-functional silencer at a time, that should be ok to tweak and modify at will.

    • Pete – TFB Writer

      It’s weird for sure.

    • Budogunner

      Step 1 of the NFA Hobby:

      Accept that US Gun Law makes a NO sense but commit to following it like scripture anyway.

      • Mattie Dimes

        Sadly, this is indeed a major canon of the Stamp Collector’s Bible. Thou shalt never understand thine BATFE, thou shalt only abide.

  • David Harmon

    You could point to the Form 1 forums as well. There is a wealth of information freely available there, as well as a few machinists that specialize in machining pre-stamp form 1 builds. Sort of like an 80% lower or something of that nature.

    • Pete – TFB Writer

      I’m definitely covering the forums in the “Resources” section in Part 2.

      • David Harmon

        Excellent. This is a great topic IMO.

        • Pete – TFB Writer

          I would have never been able to build my own or write this series without the experts in the forums, especially over in the ‘Build It Yourself’ section at AR15.com.

          • Gary Kirk

            Arf.Com.. Gotta love em, and I do.. Lotta things you “could” do.. But most likely shouldn’t..

          • Pete – TFB Writer

            Solid people over there in the tech forums.

          • Gary Kirk

            Just don’t mention an AK…

          • Gary Kirk

            My point exactly.. Lotta good advice, only problem is it’s more than often offset by the Tommy tacticool, that knows more than any armorer of “X” firearm

  • Lee

    I doubt i will ever make my own supressor, but im definitely learning alot with this article. This is very good stuff. If you guys ever create a best of section for this website, this should go in there.

    • Pete – TFB Writer

      You never know. Lots of fun. Thanks for reading!

  • Steve Martinovich

    Shame suppressors are prohibited in Canada, it would be fun to build one and also save my ears at the range.

  • AndyT

    Form 1’s are addicting. I’m on #4 now. The forums that are out there are really great and there’s quite a bit of collective knowledge out there. Of note it is legal for a 07/02 to repair your form 1 can but not build it. And as an individual you are allowed to build but not repair. Funny right?

    • Twilight sparkle

      See that not repairing thing doesn’t make any sense to me, by that same logic I’d be able to build a parts kit gun, but not repair it.

    • Enough with the BS

      The “can make but not repair” myth rears its head again.

      You can repair your Form 1 build. It is part of “making” — it’s not as if you filed a “There, I’m done now” report with BATFE.

      • kcshooter

        Are you a lawyer? Don’t answer – its rhetorical. I can tell you aren’t.

  • thedonn007

    I submitted my first from 1 about a month ago. I will wait for it to come back before I buy my parts. It will be for projectiles 9 mm and smaller. I am thinking an 8″ x 1.375″ titanium tube with radial SS baffles.

  • Austin

    Would a design that uses something else as baffles that can be switched out (like say an oil filter) count as a repair?

    • Gary Kirk

      Anything that involves replacement of “ANY” part of said suppressor

      • Austin

        Oh well, the oil filter adapter is only like $80 before the stamp

        • Just do a regular silence. Oil filters are such novelty things to not be worth it.

        • Budogunner

          I can’t find it right now, but I seem to remember the ATF revisiting those oil filter adapters and saying you could only use one filter before sending it off to an SOT to replace it.

          Citation definitely needed but as in all things NFA it is NEVER safe to look for loopholes. Examples: Akins Accelerator, first soda can launcher upper design, pistol buffer tunes and the evils of shoulder contact, etc.

          • Austin

            OK the arm brace thing was because idiots kept bugging them

        • Gary Kirk

          Most of the oil filter adapters do not cover all of the ports in the filter, and therefore cause an extreme amount of blowback to the shooter..

      • Enough with the BS

        Please provide documentation of ANY prosecution of a person for doing repair work on their Form 1 suppressor.

        You can’t — as it has never happened. Enough with this stupid boogeyman tale.

        • Pete – TFB Writer

          Only an SOT can repair a silencer. It’s right there in the regs. There are no exceptions for Form 1 builds.

          Just because “no one” has been prosecuted doesn’t make it legal.

          Do what you want, but I have a responsibility to report facts.

  • marathag

    Cutting oil: For drilling an cutting titanium
    Not all cutting oils are created equal.
    Different choice for steel and aluminum can make the difference between thinking you’re drilling thru cheese vs drilling an old, chromed Pontiac bumper, trying to melt your way thru the material than drilling it.

    For end mills here, look for center cutting mills.

    • Gary Kirk

      You mean pilot tipped?

      • marathag

        If you can plunge mill with it, it should work OK, but as a general rule, 2 flute one will do better with drilling.

        • Gary Kirk

          With very little pressure, and a lot of oil.. Drilling thin normally does better with the higher cut edge bits, at spec’d speed, with low pressure.. Or use a stepped bit. But those aren’t exactly machinist grade normally

          • marathag

            Thats the trick with drilling with end mills, slow, just don’t shove in like a drillpress going into pine.

            With Ti, a safety note, it can catch fire with machining if it gets too hot.
            It’s pyrophoric, just like magnesium. finer the particle, the more dangerous it gets.

            And don’t try to put out metalfire with water.
            Have sand around.

          • Gary Kirk

            Yep, have a scar on my wrist from core drilling out old al anchored railing..

  • Great post. Well written and explained. I also think it is a good idea to know how to make things like this as it helps you better understand how it works even if you buy rather than make one.

  • Gary Kirk

    Pete, will you be publishing the completion of this project? Because I would definitely pick up a copy.. Or at least do a comprehensive overlook upon completion of this project

  • Enough with the BS

    Stop inventing problems and making things more difficult than they need to be.

    THERE IS ABSOLUTELY NO FRIGGIN’ REASON TO INCLUDE A SKETCH OR DIAGRAM WITH YOUR FORM 1 TO THE BATFE.

    Idiots like you have brought about more BAD policy letters from the BATFE than the entire gun-control lobby and both chambers of Congress combined.

    You are not a lawyer? THEN STOP INVENTING LEGAL PROBLEMS. BATFE wants length and caliber on the Form 1. So provide that, and then SHUT THE HELL UP with nonsense scare-mongering about delays and “further information” roadblocks.

    • Pete – TFB Writer

      Did you even read the article? That sketch was for me, not the ATF.

      So, I write I how-to on legally building silencers and somehow I’m creating legal problems?

      Log off the internet. It’s not for you.

    • uisconfruzed

      Switch to decaf Skippy.

    • kcshooter

      Sounds like somebody’s cranky about their Sig brace…

  • Michael P.

    Nice work!! Thanks for sharing.

  • Dragonheart

    If you have the skills, the equipment, the tooling, the plans, the materials, the funds, the time, and the want, it makes sense to make one. Unfortunately, the vast majority of shooters and handloaders have little or none of the above other than possibly for the want and time. If they have the funds better to just buy one that you know will work.

    • itsmefool

      Plus, the warranty, if the thing comes from a reliable manufacturer!

    • AlDeLarge

      You can buy all the undrilled parts online for a basic design. They sell pre-shaped, center-punched freeze plugs on Amazon, and “Maglite storage containers.” I saw a solvent trap kit that would only need the end cap drilled and all the mesh screens unglued.

  • Trent Tyre

    Where can I find those non drilled titanium baffle stacks pictured above? I would much rather use those than freeze plugs

  • Matheus Grunt

    The only Law regarding arms that is legitimate is the 2nd Amendment, along with legitimate laws elsewhere that support that 2A & the rest of the BOR/Constitution. Any kind of “law” that impedes, restricts or otherwise infringes on our right to arms is unjust, aka, unlawful & has no power. The main reason why so many go to prison/jail is because nobody is ever willing to actually defend the Constitution from law breakers who are intent on enforcing whatever the government has told them is their job. Wrong. If we resisted & organized to stop this kind of tyranny/lawlessness (& others too not relating to the 2A), this kind of crap would not happen, or at the least, it would be very seldom after awhile because the cops would be afraid to enforce those unjust laws anymore for fear of being taken down.

    Taking a man’s arms & that includes anything that accompanies or is useful in weapons, without a dang good reason (Example: Such as that person was witnessed by another attempting to murder someone or actually did it but was convicted also), is a violation of the 2nd, 4th, 5th & 14th Amendments, along with various federal laws also. But, the govt we have had for too long now does what it wants & we just keep on letting them do it.

  • TR

    A note regarding flash hider suppressors for those of the Viet Nam War generation. There was an incredible flash hider designed and made for the XM 177. It worked so well at reducing the flash and noise level that the ATF classified it a suppressor. In the past, some of these have popped up at gun shows with the seller not knowing these are NFA items. There are probably crates of these sitting in some military depot somewhere in the States and if so may be available to both military and LEO’s.
    Be aware of this item.
    Always, if you are inclined to build a firearm or suppressor, contact your local ATF office and do the build legal. I have worked with the ATF for near 30 years through the Film & TV Industry. They are there to help you do it legal.

  • Belen Jorosa

    Good discussion ! For my two cents if you need to fill out a ATF Form 1 (5320.1) , my friend filled out and esigned a blank version here http://goo.gl/H0ZFYF

  • Liddie Afork

    Thought-provoking ideas – For my two cents , if someone is searching for a IRS W-9 , my colleagues came across a template form here http://goo.gl/Sqt04N