30 cal can - all you need to make one

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.

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30 cal can - all you need to make one

Post by CMV » Wed Jan 20, 2016 9:24 pm

Here is a simple 30 cal can. It is not elegant but it works. Intent is for something for others to copy with basic machine tools & amateur/hobbyist skill level. I'll list the materials I used - but use whatever you want. I would recommend substituting the 2024 I used for stainless if you want to do more than 300BLK subs (which is all this will see).

Will get some video & do a side-by-side comparison with a Liberty Freedom .308 hopefully this weekend. This will be primarily used for 300BLK but should be good for up to .308WIN semiauto.

I have no CAD skills, but here is a drawing with pertinent information:

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Materials list and where you can buy them (or buy whatever from wherever you choose):

4130 seamless chrome/moly tube, 1 1/2" OD x .058 wall. Stock Car Steel, $4.26/ft. TUBE
2024 AL tube, 1 3/8"OD x .065 wall. Online Metals, $34.91/ft. SPACERS
6AL-4V TI, 1 1/2" OD. Titanium Joe, $150.48/ft. END CAPS
416 stainless steel, 1 1/2" OD. Online Metals, $31.80/ft. BAFFLES

Tools needed:

Lathe
Mill (only if clipping)
RH turning tool with rear clearance
U drill (or 3/8 if you want a little bigger or not a special purchase)
5/16 or 3/8 brazed carbide bits or HSS blanks. The smaller size means much less grinding to get the clearance to cut the inside of the cones.
Cutoff tool
37/64 drill
5/8-24 tap or small enough threading tool to get in the 37/64 hole
3/8 endmill suitable for your baffle material (only of clipping)
Profiling tool or blank/brazed bit you grind into one
Threading tool
Knurling tool (if you want)
Spanner (if you want my style cap)
Bench grinder - whatever you use you will need to sharpen often if using TI or SS. Cutting the insides of the cones is a lot of work for the little tool needed for clearance
Caliper & micrometer
Coolant - search for my thread for a cheap flood system if you don't have.

I think that's all I used - probably forgetting some little widget or 2. I will Cerakote it soon & have an engraving machine but you'll need some way to finish it. If you use the 4130 like I did you can blue it.

Next is a crap ton of pictures that should answer a lot of questions

This is a closeup of the chamfer on the spacers. I shamelessly stole this idea from Kyle. This lets the baffle recess into the spacer and gives it a bearing surface to center it. This does take away from the spacing a little.
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Closeup of how I clipped the baffles. I did not clip the blast baffle. I cut a little under half the width. There are many variations on how to clip baffles so you will need to research on how to do yours. Or don't do it at all. What I did here is pretty mild I think and may have no effect.
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Top & bottom view of cone baffles
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Dimensions
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Tube threading. 20 TPI
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Blast baffle. Same as the others but thicker. I went for 0.050" for the regular baffles (which all came out -0.000 to +0.008 of that). Not clipped & 0.065" thickness for this one.
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End caps. I still have some meat to remove. The rear one requires a spanner to install/remove. It had a shoulder like the other but I boogered it up & was too lazy to start over since threading the TI takes me forever.
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Rear end cap on my 300BLK barrel
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Baffle stack
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Thanks to my wonderful photography you CAN'T see that this weighs 18.2 oz
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All the guts
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Drawing in .jpg in case the .png above doesn't display
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Disclaimer: All NFA rules apply. Have your stamp in hand (or live somewhere you can make whatever, whenever) before starting this project. I am not an engineer, nor a machinist, nor a professional silencer manufacturer, nor a lawyer - follow these plans at your own risk. If you follow this exactly and ruin your gun/eyes/hands/fingers/etc it's your fault, not mine. You are making something potentially dangerous following free plans you found on the internet. I strongly encourage you to read all comments in this thread and seek the advice of others before starting this project if you are a novice. Some assembly required. Do not eat. All models over the age of 18. NO FREEZE PLUGS OR MAGLIGHTS WERE HARMED IN THE MAKING OF THIS SUPPRESSOR

Lastly, feel free to make this a "community build" by offering suggestions to make it better or easier to make. I don't expect this to be a Thunderbeast 30P-1. Again, the goal was to make a good (not exceptional) performing build that's easy enough for a novice with basic lathe tools & basic machining skills. I'll do elegant next time... :)
Last edited by CMV on Sat Jan 23, 2016 4:16 pm, edited 1 time in total.
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Re: 30 cal can - all you need to make one

Post by propeine » Wed Jan 20, 2016 10:53 pm

You sir are a gentleman and a scholar!
I appreciate the full prints after our recent discussion and I know how long it takes to stop and take pictures as well.

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Re: 30 cal can - all you need to make one

Post by Capt. Link. » Wed Jan 20, 2016 11:02 pm

Your machining keeps getting better and better.I really like the knurling and your finish cuts are very clean.I hear if you drive to the range with the camera in your armpit the battery's will last until the first blast of cold air goes up your skirt. :D
-CL
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

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Re: 30 cal can - all you need to make one

Post by Hasdrubal » Thu Jan 21, 2016 4:07 am

I'm working on a .223 can, but was afraid having a beveled front on the spacer/cone interface would not be as stable as making a flat bevel and a notched rear surface on the cones. In my time lurking here I don't recall any major discussion on the subject. If your way works, I think I'll follow your example in the future. Thanks for all the info, and especially the photos.

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Re: 30 cal can - all you need to make one

Post by propeine » Thu Jan 21, 2016 9:10 am

Just wanted to share my trick for measuring on the angled portion of the cones if you have an integral spacer. I found I was leaving as much as .030 extra on my thickness based on math and drawings alone.

This is a "Bucky ball" which just so happens to be exactly 5mm. Neodymium magnet balls that come in packs of like 200. Much cheaper than buying new micrometers.

Image

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Re: 30 cal can - all you need to make one

Post by CMV » Thu Jan 21, 2016 1:59 pm

Hasdrubal wrote:I'm working on a .223 can, but was afraid having a beveled front on the spacer/cone interface would not be as stable as making a flat bevel and a notched rear surface on the cones. In my time lurking here I don't recall any major discussion on the subject. If your way works, I think I'll follow your example in the future. Thanks for all the info, and especially the photos.
Seemed to work for Kyle. I've done it in other applications & the spacers hold up fine, but never tried with AL. 2024 is strong for AL but I used it because that's what I had on hand that fit the chrome moly tube best.

I should probably just amend the above to call out stainless or chrome/moly for the spacers. I'm sure people will look while shopping & say "6061 is MUCH less expensive, I'll just use that instead". 300BLK subs are around the same pressure as mild 9mm & about 1/2 of .308 WIN
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Re: 30 cal can - all you need to make one

Post by EXPERIMENTAL » Thu Jan 21, 2016 4:15 pm

BEST BUILD POST TO DATE..... and yes I have seen the "Links to complete build" thread

Included:
-materials
-instructions
-pictures
-measurements
-baffle spacing


Bravo Sir, Bravo!

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Re: 30 cal can - all you need to make one

Post by CMV » Fri Jan 22, 2016 5:54 pm

Here is the video of its performance. Left is the build above, right is a Liberty Freedom. Both guns are AR-15s w/ 16" barrels. Supersonic load is a 110gr V-MAX 2400fps, subsonic load is a 220gr SMK at 1050 fps. He loaded 1 more supersonic than I did - oops.

https://youtu.be/Mj8lAg2uAGc

We shot a lot more but camera/weather/wind/rifles not cooperating at all. Sorry about the wind noise - crappy weather day here today (but got a 'snow day' off work so got to play :) ) Anyway, supersonic ammo sounded the same from both suppressors. Very, very close. I thought his sounded quieter on subs, he thought mine did, so perspective played a part. On the video, they sound very close to same sound level but I'd give the win to the Liberty on subs. But I'd call either one "Hollywood".

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I don't know how all the different commercial .308 cans compare to each other, but I don't think the Liberty Freedom is a slouch. I would guess it's somewhere near the top of the heap? So for mine to do so well compared to it, I'm thrilled!
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Re: 30 cal can - all you need to make one

Post by Capt. Link. » Fri Jan 22, 2016 7:59 pm

That's a great sounding suppressor.I can't hear much difference between the two.
-CL
The only reason after 243 years the government now wants to disarm you is they intend to do something you would shoot them for!
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Re: 30 cal can - all you need to make one

Post by silencer_kid » Fri Jan 22, 2016 10:04 pm

just a couple of questions.
1) the ID of tube = OD of spacers and cones. how do they fit?
2) what type of thread are you specifying?
3) sounds great, what type of blowback are you getting?

do you want CNC step files for these parts? i can easily make them in CAD.

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Re: 30 cal can - all you need to make one

Post by 0101silent » Fri Jan 22, 2016 10:50 pm

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Re: 30 cal can - all you need to make one

Post by yondering » Fri Jan 22, 2016 11:20 pm

CMV wrote:
Hasdrubal wrote:I'm working on a .223 can, but was afraid having a beveled front on the spacer/cone interface would not be as stable as making a flat bevel and a notched rear surface on the cones. In my time lurking here I don't recall any major discussion on the subject. If your way works, I think I'll follow your example in the future. Thanks for all the info, and especially the photos.
Seemed to work for Kyle. I've done it in other applications & the spacers hold up fine, but never tried with AL. 2024 is strong for AL but I used it because that's what I had on hand that fit the chrome moly tube best.

I should probably just amend the above to call out stainless or chrome/moly for the spacers. I'm sure people will look while shopping & say "6061 is MUCH less expensive, I'll just use that instead". 300BLK subs are around the same pressure as mild 9mm & about 1/2 of .308 WIN
For 300 Blk subs and 9mm only you could make that whole can out of 6061 and save some weight, no steel needed.

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Re: 30 cal can - all you need to make one

Post by CMV » Sat Jan 23, 2016 8:52 am

6061 is best left for making fixtures. 7075 & 2024 are superior flavors of aluminum.

Design above is for .308 WIN so making it with 6061 would severely limit the applications. In the US, it wouldn't make much sense to make (or buy) a rifle suppressor that could only withstand subsonic ammo.

I would not shoot .355 projectiles through a .368 bore.

But yes it would be lighter made from all AL. It would also be lighter made from all TI.

Griffin Armament Optimus - 18.5 oz
AAC 762-SD - 23.2 oz
YHM Phanton LTA - 20 oz
Thunder Beast 30P-1 - 16 oz
AAC Cyclone - 22.4 oz
Liberty Freedom -22.5 oz
Huntertown Kestrel - 18 oz

I don't think the 18.2oz weight compares unfavorably.

Also - if it were specifically a 300BLK sub build and you wanted it to perform the best on only that one caliber the baffle spacing would need to change. It's good as it is, but would perform better on 300BLK subs with the first spacer about 1.300" and the remainder at 0.700". You have to do the math to get exactly what would fit or just adjust a spacer somewhere to compensate, but that would be better spacing for 300BLK subs. Might be another spacing arrangement that would be even better but I'm not spending the $200 to find out. I doubt my 'calibrated ear' would be able to tell anyway.
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Re: 30 cal can - all you need to make one

Post by CMV » Sat Jan 23, 2016 10:26 am

0101silent wrote:Thanks for the detailed design specs. The silencer looked and sounded great.
Could you list the weights of the components? It would make it easy to estimate weight gains or losses by substituting different materials.
My postal scale isn't precise enough for individual components. Weighed in grams on my powder scale & converted.

Image

18.25 oz all added up, but I can't weigh the tube precisely since it's too heavy for my powder scale. Assembled or taken apart, I get 18.2 oz on the postage scale so that's gonna be real close to what it weighs.
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Re: 30 cal can - all you need to make one

Post by CMV » Sat Jan 23, 2016 10:58 am

silencer_kid wrote:just a couple of questions.
1) the ID of tube = OD of spacers and cones. how do they fit?
2) what type of thread are you specifying?
3) sounds great, what type of blowback are you getting?

do you want CNC step files for these parts? i can easily make them in CAD.
1. reread first post. I have a measuring error somewhere. I have between .005-.008 clearance. It assembles easily clean & disassembles without a whole lot of fuss dirty. I'm not beating the baffles in/out.

2. Thread is 20 TPI, .031 single depth, using this carbide insert tool:
Image

3. I have no way to measure that. No more 'crap from the ejection port' than I've experienced with other suppressed ARs shooting 300 BLK. I was using the red dot on a 45° mount on my rifle. That tends to put more ejection port crap in your face & it wasn't bad.

I have no need for CNC files. I'm primitive & don't even have DROs on my machines.
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Re: 30 cal can - all you need to make one

Post by 0101silent » Sat Jan 23, 2016 1:32 pm

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Re: 30 cal can - all you need to make one

Post by CMV » Sat Jan 23, 2016 3:38 pm

OK - here's the problem. Tube ID is 1.393. They only sell .049 & .058 wall chrome/moly tube at SCS & I know I bought the .058 wall. These dimensions mean I have .0535 wall tube which is right in the middle of those sizes. I did not bore the tube. In my pic in first post of measuring the tube where it shows 0.0575" on the wall, I have the flat blades all the way in the tube thinking I didn't want to measure on the threads. But measuring something round that way will come out oversize. I need to get some of those magnetic spheres for my micrometer and then use it in the future. Luckily I'm not working on space shuttle parts in my garage...

So I have .008" clearance. Amended the drawings and 1st post to avoid confusion later on.

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Re: 30 cal can - all you need to make one

Post by silencer_kid » Sat Jan 23, 2016 8:18 pm

CMV wrote: 1. reread first post. I have a measuring error somewhere. I have between .005-.008 clearance. It assembles easily clean & disassembles without a whole lot of fuss dirty. I'm not beating the baffles in/out.

2. Thread is 20 TPI, .031 single depth, using this carbide insert tool:
Image

3. I have no way to measure that. No more 'crap from the ejection port' than I've experienced with other suppressed ARs shooting 300 BLK. I was using the red dot on a 45° mount on my rifle. That tends to put more ejection port crap in your face & it wasn't bad.

I have no need for CNC files. I'm primitive & don't even have DROs on my machines.
what i mean is, you used UNF (doesnt look like its to-spec UNF, doesnt need to be, but what type of threading is what i am asking) ??
you also have 20 and 24 TPI used. why two?

also, unless you machine the ID and OD of tubes true they will not be round. this is tolerable if accounted for in the design.

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Re: 30 cal can - all you need to make one

Post by fastfire » Sat Jan 23, 2016 8:33 pm

silencer_kid wrote:
CMV wrote: 1. reread first post. I have a measuring error somewhere. I have between .005-.008 clearance. It assembles easily clean & disassembles without a whole lot of fuss dirty. I'm not beating the baffles in/out.

2. Thread is 20 TPI, .031 single depth, using this carbide insert tool:
Image

3. I have no way to measure that. No more 'crap from the ejection port' than I've experienced with other suppressed ARs shooting 300 BLK. I was using the red dot on a 45° mount on my rifle. That tends to put more ejection port crap in your face & it wasn't bad.

I have no need for CNC files. I'm primitive & don't even have DROs on my machines.
what i mean is, you used UNF (doesnt look like its to-spec UNF, doesnt need to be, but what type of threading is what i am asking) ??
you also have 20 and 24 TPI used. why two?

also, unless you machine the ID and OD of tubes true they will not be round. this is tolerable if accounted for in the design.
The 24 tpi most likely was to match the the barrel thread. 30CAL =5/8X24

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Re: 30 cal can - all you need to make one

Post by silencer_kid » Sat Jan 23, 2016 8:37 pm

fastfire wrote:
The 24 tpi most likely was to match the the barrel thread. 30CAL =5/8X24
so why not just stick with 24tpi for everything, why use 20tpi when 24tpi was already going?

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Re: 30 cal can - all you need to make one

Post by CMV » Sat Jan 23, 2016 10:41 pm

Moving the lever on the gearbox isn't all that hard. If I had to swap out gears or something, yeah I'd just leave it all the same. But since it takes me all of 2 seconds to change I use what I feel is appropriate.
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Re: 30 cal can - all you need to make one

Post by CMV » Sun Jan 24, 2016 5:52 pm

Accuracy seems ok. Very little POI shift which surprised me. This is 5 suppressed & 5 unsuppressed.

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Re: 30 cal can - all you need to make one

Post by MG_Willy » Mon Jan 25, 2016 1:09 pm

Beautiful... I have a couple questions.. 1. can I copy it :) hehehe and 2. what is the length of your baffle stack and spacers combined. trying to understand your spacers are 6.32" total with the cones also providing a little space but I cant determine that. and 3.. how much space is the space between your threads? Im assuming that your baffle stack length and the spacing between your threads be close but might over lap a tiny bit to provide a rock solid fit when tightened down.

Looks beautiful and a GREAT write up.

thanks

MG_Willy

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Re: 30 cal can - all you need to make one

Post by CMV » Mon Jan 25, 2016 8:11 pm

MG_Willy wrote:Beautiful... I have a couple questions.. 1. can I copy it :) hehehe and 2. what is the length of your baffle stack and spacers combined. trying to understand your spacers are 6.32" total with the cones also providing a little space but I cant determine that. and 3.. how much space is the space between your threads? Im assuming that your baffle stack length and the spacing between your threads be close but might over lap a tiny bit to provide a rock solid fit when tightened down.

Looks beautiful and a GREAT write up.

thanks

MG_Willy
1. Of course. I posted all this just so it could be copied.
2. Roughly 7". 8" tube, each end cap screws in appx .500"
3. Not sure what you mean by 'how much space is the space between your threads?'. I didn't measure precisely, but the tube internal threads are longer than the threads on the endcap. I threaded each end at least .600" into the tube.
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Re: 30 cal can - all you need to make one

Post by MG_Willy » Mon Jan 25, 2016 9:22 pm

Thanks that is what I was curious about.. it does look great.

Thanks for the info.
CMV wrote:
MG_Willy wrote:Beautiful... I have a couple questions.. 1. can I copy it :) hehehe and 2. what is the length of your baffle stack and spacers combined. trying to understand your spacers are 6.32" total with the cones also providing a little space but I cant determine that. and 3.. how much space is the space between your threads? Im assuming that your baffle stack length and the spacing between your threads be close but might over lap a tiny bit to provide a rock solid fit when tightened down.

Looks beautiful and a GREAT write up.

thanks

MG_Willy
1. Of course. I posted all this just so it could be copied.
2. Roughly 7". 8" tube, each end cap screws in appx .500"
3. Not sure what you mean by 'how much space is the space between your threads?'. I didn't measure precisely, but the tube internal threads are longer than the threads on the endcap. I threaded each end at least .600" into the tube.

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