Yes, it can be legal to make a silencer. For everything Form-1, from silencer designs that are easily made, to filing forms with the BATF, to 3D modeling. Remember, you must have an approved BATF Form-1 to make a silencer. All NFA laws apply.
Hi all! First, a bit about me. I'm a mechanical engineer with some machining experience. I have a lathe and a mill, so in general if you suggest something, I can make it, or at least figure out how I have never made a suppressor before.
I'm looking at building a 300 blackout pistol with a suppressor. I'm thinking I'll go with a 10.5" barrel and a 10"x1.5"OD suppressor. I'm thinking 0.07" wall thickness for an ID of ~1.36". Is that big enough? I'm debating between K baffles and a monolithic design. It seems like K baffles are strictly better, but the monolithic would be sooo much easier to make. The plan is to use all titanium possibly except for the end cap that adapts to the barrel. I'm working through the forms right now, are there resources for help with filling them out?
Veggicide wrote:Hi all! First, a bit about me. I'm a mechanical engineer with some machining experience. I have a lathe and a mill, so in general if you suggest something, I can make it, or at least figure out how I have never made a suppressor before.
I'm looking at building a 300 blackout pistol with a suppressor. I'm thinking I'll go with a 10.5" barrel and a 10"x1.5"OD suppressor. I'm thinking 0.07" wall thickness for an ID of ~1.36". Is that big enough? I'm debating between K baffles and a monolithic design. It seems like K baffles are strictly better, but the monolithic would be sooo much easier to make. The plan is to use all titanium possibly except for the end cap that adapts to the barrel. I'm working through the forms right now, are there resources for help with filling them out?
Thanks in advance!
The Eform system is back online so that is an option. or you can fill them out and send them in. just remember your RPQ's (responsible person questionnaire.
as for the suppressor if your going to run subs and supers .070" wall is more than thick enough if running Ti. If your going to run subs only you could go quite a bit thinner. K's or better yet modified k's would work very well for subs, radials would be a good middle of the road and 60's would still work decently if you plan to run sub/supers. i'm not a big fan of monolithic's.
If you plan to run supers you may want to add a 17-4 baffle for the blast baffle.
As posted above, the e-file system is back up and approvals have been seen as early as 10 days. Yes, a 10 day approval.
1.5 x 10 w/ .07 wall is vast overkill, especially for 300blk subs.
1.375 x 8, depending on baffles, would be plenty. Don't let this deter you from trying to fill a role or rifle forearm.
Ti is a condender, but don't rule out Al for a sub only can. 17-4 is a no brainer. Can be made super thin and very resilient to corrosive environments.
K's work great, but, I'll be honest, won't be easy for a first time maker. Not to machine, but to get the porting correct. POI shift can be greatly affected by a poorly made K, let alone sound reduction.
Monocore is doable, provided you copy or follow a proven design.
Cones or radials, cones being easier, will be the safest option. They'll lack nothing in sound reduction and are very forgiving on poor machining. Tons of threads here and on the form 1 boards for a 300blk suppressor. Especially a cone build.
Thanks for the quick replies. Is there a good reference sheet for baffle designs? I'm trying to see if there is a good pinned topic, but not finding anything that has things like angles, ect. I'll look up other 300 builds as well.
I do think I want to run 1.5 OD to fill out my fore grip (purely looks ), but I'd be super happy to drop to 8" if it will still have good performance! Where do people tend to get their metals? I'm looking on ebay, speedy metals, and a local shop. Is there a better place? Would you make the baffles out of 17-4 as well?
In my signature is a link to the completed builds section. If you're serious about learning most things silencer related, it would serve you to read it. A lot of pics may have been dropped, but tons of info in the written word.
Online metals can be pricey and I've heard plenty stories about their tubing being out of spec.
I've order countless materials from ebay and McMaster w/o issues. There's a guy in Isreal (ebay seller) w/ good prices on Ti drops, especially if your buying more than a little.
Personally, if I was making it for a sub only 300blk build, no, I wouldn't make them all out of SS. Ti maybe. Definitely 1or 2 SS and the rest Al. It also depends on your design and personal tendencies. Way too many people think you need to clean a silencer. They're all wrapped up in using the dip or wanting to wet tumble the parts. The only time I open a silencer, for cleaning, is if I've been using any type of filler in the load workup. Other than this, the threads will get brushed off and relubed. I don't perform any maintenance to the actual baffles. I would if I saw POI shifting, but none w/o. I consider them to be consumables. By the time a 22lr suppressor is filled beyond the point of use or being able to knock the chunks off, it's time to just send off another stamp and make a new one.
I've been going through the completed build section, very educational.
I've been seeing conflicting info on using aluminum baffles. It would be nice to machine aluminum rather than steel or TI, but I want to make something that lasts. I'm not sure I buy your idea of making a new one when it clogs up, but if that is the case then I probably would go alum. I asume 7075 is the grade? Thanks for ebay info!
garredondojr wrote:
The Eform system is back online so that is an option. or you can fill them out and send them in. just remember your RPQ's (responsible person questionnaire.
I just got to this point on the form. I'm filling out as an individual, so do I just need to put myself for the RP? What should my title be?
Ecco Machine uses aluminum baffles in a thin Ti tube for one of his pistol suppressors. he did a torture test and did manage to frag the baffles but it took quite a bit of abuse to get it there. the tube held up just fine amazingly!
So like mentioned before if your running subs only aluminum would be a viable option that would save weight, cost, and ease if machineability,
7075 and 2024 are both good options. stay away from 6061 it doesn't hold up well to the heat.
Veggicide wrote:Hi all! First, a bit about me. I'm a mechanical engineer with some machining experience. I have a lathe and a mill, so in general if you suggest something, I can make it, or at least figure out how I have never made a suppressor before.
I'm looking at building a 300 blackout pistol with a suppressor. I'm thinking I'll go with a 10.5" barrel and a 10"x1.5"OD suppressor. I'm thinking 0.07" wall thickness for an ID of ~1.36". Is that big enough? I'm debating between K baffles and a monolithic design. It seems like K baffles are strictly better, but the monolithic would be sooo much easier to make. The plan is to use all titanium possibly except for the end cap that adapts to the barrel. I'm working through the forms right now, are there resources for help with filling them out?
Thanks in advance!
Whats the host for the build.Will the suppressor be integral or a separate device.Will it use supersonic or subsonic ammo.A good suppressor core to cover the range of pressures might be a hybrid of cones & K's.I know monocores are all the rage but when you mess up the machining on a cone you just rebuild one cone and not the whole stack.I would use 17-4 for at least the first few baffles then you could use either Ti or 7075 AL for the rest of the stack.The one downside of using AL is it must be anodized and if you wish the best it would be hard anodizing.You can't do that at home and few shops can do it for you.Let us know the details so any information will be correct for the design.
The only reason after 243 years the government now wants to disarm you is they intend to do something you would shoot them for!
http://www.silencertalk.com/forum/viewtopic.php?f=10&t=79895
garredondojr wrote: why must the baffles be anodized?
When faced with a harsh environment, such as the interior of a suppressor, Aluminum will degrade quite rapidly unless properly protected. The oxide layer, formed during anodizing, is what increases the corrosion and abrasion resistance. While the anodized exterior will be heat resistant well passed the melting point of the base Aluminum, don't expect it to stop anything from melting.
I used aluminum on my blackout baffles, however, I don't shoot supers (which defeats my purpose of making a suppressor). My sub loads don't get the can terribly hot.
I don't do endless mag dumps, and I don't shoot it on a full auto lower either. I just shoot it how I normally would. In short, I don't run it excessively hot and its' held up fine.
If you get aluminum hot enough to cause problems, doesn't really make a huge difference whether you're using 7075 or 6061 or whatever. The heat ceiling is similar enough for both grades. If you'd get one hot enough to damage it, wouldn't be doing any favors for any other grade either.
Shooting a steady diet of supers though, I would use really thin stainless baffles.
A lot of guys also use onlinemetals for a lot of their project supplies.
K's work great, but, I'll be honest, won't be easy for a first time maker. Not to machine, but to get the porting correct. POI shift can be greatly affected by a poorly made K, let alone sound reduction.
hes got a copy of my cad files and mine definitely work for 300subs (although they're designed for a 1.625" tube.)
OP, if you copy my Ks, there's no need to make it 11" long like mine. I'd probably do 8-9" if I were to start over. Also, I would very highly recommend slightly modifying my design making the Ks nest into each other like these:
300 blackout form 1: http://www.silencertalk.com/forum/viewtopic.php?f=10&t=137293
5.56 form 1:
http://www.silencertalk.com/forum/viewtopic.php?f=10&t=141800&p=955647#p955647
I'll probably be shooting mostly subs, but I'd like the freedom to shoot supers without having to worry about killing my silencer, so I think I'll go for stainless.
Fishman, thanks a bunch for the CAD! I'm designing mine from the ground up, but I'm getting a lot of inspiration from the work you did! I'll probably start a separate thread here shortly showing the design steps I'm taking.
John A. wrote:I used aluminum on my blackout baffles, however, I don't shoot supers (which defeats my purpose of making a suppressor). My sub loads don't get the can terribly hot.
Shooting a steady diet of supers though, I would use really thin stainless baffles.
A lot of guys also use onlinemetals for a lot of their project supplies.
Could you give me an idea of what you mean by super thin? I'm thinking of going to about 0.030". I'm not confident I can machine much thinner than that. I'm trying to run some simulations to figure out the pressure differentials and flows, but SimFlow CFD is kicking my butt.
,030 is thin. You're just holding back a puff of smoke.
Only reason I recommended steel over aluminum was because when shooting supers is the extra powder and heat mostly. Especially if shooting a bunch of them in short order so you don't melt your baffles down into mush.
Aluminum works fine for shooting subs. Those don't really get any hotter than any other pistol can.
Veggicide wrote:
Could you give me an idea of what you mean by super thin? I'm thinking of going to about 0.030". I'm not confident I can machine much thinner than that. I'm trying to run some simulations to figure out the pressure differentials and flows, but SimFlow CFD is kicking my butt.
Like John said, .030" is really thin. I only use Ti that thin on my Ocelot Micro, a .22 LR only can. I have to run 40 pitch threads on those, and concentricity is absolutely critical. As in, I indicate the tubes to <.0005" before threading. And it's also tricky to get such thin tubing tight enough in the chuck that it won't move under tool load without distorting it; my 13" 4 jaw has so much surface area grabbing on the 1" tubing I use that I can get away with it, but in many chucks you'd likely end up having to make a snug fitting slug to go inside.
My pistol cans and ultralight rifle cans are .035" wall with 36 pitch threads, but my medium and heavy duty rifle cans are .045" & 30 pitch and .070" & 24 pitch respectively, the latter being thinned to .050" in the centers.
If you're going direct thread, you can make a 1.5" x 8" can with .045" wall Ti tube and all 17-4 internals that will come in under one pound. 17-4 is tough stuff, can make baffles pretty thin, especially if you're not going to be subjecting it to heavy rapid fire. Like, .050" thick blast baffle and .025"-.030" for the rest.
ECCO Machine wrote:
Like John said, .030" is really thin. I only use Ti that thin on my Ocelot Micro, a .22 LR only can. I have to run 40 pitch threads on those, and concentricity is absolutely critical. As in, I indicate the tubes to <.0005" before threading. And it's also tricky to get such thin tubing tight enough in the chuck that it won't move under tool load without distorting it; my 13" 4 jaw has so much surface area grabbing on the 1" tubing I use that I can get away with it, but in many chucks you'd likely end up having to make a snug fitting slug to go inside.
My pistol cans and ultralight rifle cans are .035" wall with 36 pitch threads, but my medium and heavy duty rifle cans are .045" & 30 pitch and .070" & 24 pitch respectively, the latter being thinned to .050" in the centers.
If you're going direct thread, you can make a 1.5" x 8" can with .045" wall Ti tube and all 17-4 internals that will come in under one pound. 17-4 is tough stuff, can make baffles pretty thin, especially if you're not going to be subjecting it to heavy rapid fire. Like, .050" thick blast baffle and .025"-.030" for the rest.
Thanks for the info. I'm planning on going thicker for the tube (currently titanium ~0.090). I know that is pretty thick, and my simulation software is showing pretty good results so far with this. I'm about to go metric on you, sorry. I'm doing 1.5 mm pitch (~17 tpi). I'll share simulation results tomorrow in a separate thread, I need to know where I'm being too conservative. The baffles are the spot I want to go to 0.03.
.09 is unnecessarily thick. Is there a reason, other than tube availability and thread depth, that you chose this number?
1.5mm pitch is quite coarse, for this application. I've never gone lower than 24tpi and typically use 28, for threading tubes. I think the lowest pitch I've seen is 20 and this was being used on the solvent trap items. I believe the only reason it was this was due to it being a legacy Maglite callout (could be wrong) and a lot of suppliers have gone to 24.
Not to be a Debbie Downer, but I wouldn't hold flow calculations too high up on the pedestal. They can help w/ certain features, but trying to plan an entire suppressor will prove quite frustrating. I design industrial burners and use Ansys in our calculations. Mind you, these are constant flows; however, I'm trying to convey that this is what I do and I have software built for the task. I've run countless impulse simulations w/ ever more variables. It's extremely difficult to replicate the conditions of a rifle barrel and even harder to know when you have them correct. I've modeled older designs that yielded greater results than top tier items using modern tech. Obviously, something in the calculations was incorrect, but that's my point. You won't know when the parameters are identical and, even then, you can't guarantee the results. Also, there's no assurances that any of this will directly coincide with decibel reduction, which is the end goal. Unless, of course, you have the proper metering equipment to quantify your results. Even then, none of this is truly helpful to the Form1 builder, doing one stamp at a time. Have fun with the process, but know that sticking to proven design principles will pay off.
Adding to T-Rex's sage advice of 28TPI, here
are the five cut sequence to reach the required .024"
minor diameter:
.007/.006/.004/.004./003
And it is important to set up the compound to ~60º
which means that on the graduated compass you set to 29.5º.
I refer to Tubalcain's* tutorial on YouTube to
refresh my memory before threading. Still remember
old WW1 Institute machinist telling a newbie to get
him a left handed crescent wrench and
"cut twice, measure once"
Personally I use a 'hand crank organ grinder' on the lathe
to control the speed and length.
Veggicide wrote:
Thanks for the info. I'm planning on going thicker for the tube (currently titanium ~0.090). I know that is pretty thick, and my simulation software is showing pretty good results so far with this. I'm about to go metric on you, sorry. I'm doing 1.5 mm pitch (~17 tpi). I'll share simulation results tomorrow in a separate thread, I need to know where I'm being too conservative. The baffles are the spot I want to go to 0.03.
There's no reason to go that thick, just gonna be heavier and more expensive. .070" is as thick as you ever need to go short of containing .50 BMG or similar monster rounds.
I also agree that M1.5 is way course. .9 to 1.0 is much more sensible.
As T-Rex said, aerodynamic flow modeling programs are not particularly useful with the high pressure, extremely high velocity and extremely short duration you're dealing with inside a suppressor. He's also correct in that even if it did, having one that looks great in flow characteristics wouldn't necessarily make for a quieter can (Look at OSS stuff). Stick to radial or cone baffles, base your design on something proven. I'm an 07/02, so can build as many baffles and cans as I want to experiment, and have done some pretty radical designs in both stacked baffles and monocores, but in the end, there's a reason all the proven centerfire cans still use cones, radials or K baffles.
Even .045 is really thicker than it needs to be for a 30 cal with a little safety cushion built in.
I went down the same road that you did on my first suppressor. I used .065" wall because I was afraid it would blow up if I went too thin.
While it will probably outlast my great grandchildren, it's excessive and unnecessary, and a lot heavier than it needs to be. I lrearned a lot making my first can. Just trying to save you some of the growing pains that I have went through.
T-Rex wrote:...Have fun with the process, but know that sticking to proven design principles will pay off.
This is really the goal I know I could probably just follow a design here and be fine, but I'm having fun playing, and besides, I'm waiting on a few other things before I can start building anyway. I need to set up a gun trust (doing it through a lawyer, so it is taking a bit longer) before filling out my form 1.
Historian wrote:Personally I use a 'hand crank organ grinder' on the lathe
to control the speed and length.
Fortunately my lathe has a reversible motor! My lathe is metric, which is why I'm going back and forth between the two. Seems everyone here is imperial.
Edit: I see what you are saying here, you actually hand crank while threading. Never tried that, maybe I will.
John A. wrote:Yeah, .090 is double excessive.
T-Rex wrote:.09 is unnecessarily thick. Is there a reason, other than tube availability and thread depth, that you chose this number?
I'll address this more in a separate thread when I can show the calculations I'm doing that have lead me here. I agree, it seems way thick, but I'm not sure where I'm going wrong. I have some hand calcs and FEA (using some autodesk software) that agree pretty well. Obviously my pressure/temperature/something assumptions are off.
Veggicide wrote:
I'll address this more in a separate thread when I can show the calculations I'm doing that have lead me here. I agree, it seems way thick, but I'm not sure where I'm going wrong. I have some hand calcs and FEA (using some autodesk software) that agree pretty well. Obviously my pressure/temperature/something assumptions are off.
I don't know what values you're putting in, but .035" wall gr. 9 Ti with 36 pitch threads withstood the pressure of .308 from a 13" barrel, and that can was already over 1,000°F when I cut loose a 25 round mag full auto. I'd suggest a little thicker for a F1 rifle can, but there's really no need to go heavier than .045" wall.
Veggicide wrote:My lathe is metric, which is why I'm going back and forth between the two. Seems everyone here is imperial.
Most machines found in the states are Imperial, as are dimensions on parts for those who aren't building every component.
I have never made a suppressor before. 
