Punkinhead's build plan

[punkinhead]

I just got the bug to make a .22LR suppressor. I'm hoping to submit the Form 1 next week. I've done a bunch of reading here to get an idea of good designs and started drawing up what mine would look like - mostly to get a length dimension to put on the Form 1.

I plan to use 1" OD 316L stainless tube. The end caps and probably the first baffle will be stainless. I haven't decided whether to make the rest of the baffles stainless or aluminum. I'd appreciate any feedback.

Some questions:

1. Should the k-baffles nest? In other words, should the right end of one baffle fit into the left end of the next baffle or should the OD of the cone be a slip fit to the ID of the tube? I've seen pictures of it done both ways and wonder if there's a preference.
2. I have a 1/2" blast chamber in front of the first baffle. Is this about right?
3. I ended up with 7 baffles. Should I take one out and shorten the suppressor?
3. The overall length comes out to 5-3/4". Is that what I put on the Form 1 or do I put 6" to give myself some wiggle room knowing I'll have months to refine the design? I know I can go shorter than what I list on the Form 1, but I'm not sure how much variation is acceptable. I'm sure the BATF doesn't want people putting down "3 feet" for length then making it any length they want.

[daviscustom]

You can make the k's interlock or just make them a snug fit in the tube.....snug fit will make them hard to get out for cleaning so you may want to consider making them interlock so they are self aligning when you tighten them up.

You could turn down the OD of the last K so that it fits inside the front cap and save .3" in length....and why not make the inside of the front cap look like the face of a K baffle?

[punkinhead]

You can make the k's interlock or just make them a snug fit in the tube.....snug fit will make them hard to get out for cleaning so you may want to consider making them interlock so they are self aligning when you tighten them up.

You could turn down the OD of the last K so that it fits inside the front cap and save .3" in length...

Here's what it would look like by interlocking the baffles and letting the forward-most baffle slide into the front cap. Does that seem too short? What's a good length target that gives enough internal volume to do a good job suppressing a .22LR?

[Dr.K]

I've never made a K, but I have been learning on a lathe every day for 3 months now.

If you go with the interlocking design, it seems you'd have to construct a jig to chuck them up in the lathe when you turn them around for backside machining. Or, you may be using a CNC rig, not sure, just an observation from a simpleton. I guess you could grip them at just the plate, but there wouldn't be much purchase from the chuck jaws.

Every design I'm seeing these days, I'm thinking on how to make it with what I have. It's been a totally different perspective.

with a tube fit design, just spin them around and tighten the jaws.

[ChimeraPrecision]

An easy way to hold k's is by slitting a piece of the tube you are going to use. Slide k in slit end and clamp in chuck

[Capt. Link.]

You can make the k's interlock or just make them a snug fit in the tube.....snug fit will make them hard to get out for cleaning so you may want to consider making them interlock so they are self aligning when you tighten them up.

You could turn down the OD of the last K so that it fits inside the front cap and save .3" in length...

Here's what it would look like by interlocking the baffles and letting the forward-most baffle slide into the front cap. Does that seem too short? What's a good length target that gives enough internal volume to do a good job suppressing a .22LR?

Your interlock is reversed you should also contemplate timing as well.I would shorten the blast space and use a Dater hole "Nice" solid plan.
I would recommend a all SS build to keep corrosion at bey.

[mollinst]

Enfield made a nice little stepped collar for doing just this.

[Enfield577]

Enfield made a nice little stepped collar for doing just this.

Sure did, here is the complete K baffle manufacturing guide with all the tooling,fixtures etc

viewtopic.php?f=10&t=81037

[Capt. Link.]

The Support is still backwards the face should support the skirt from crushing inwards not outwards."Implosion" not explosion.

[punkinhead]

Your interlock is reversed you should also contemplate timing as well.

Interesting, I don't recall coming across a picture of the interlocking being reversed from my picture. One quick & easy way to swap the interlocking would be to chamfer the left end of the baffles to match the inside taper of the previous baffle:





I probably wouldn't do it this way though - I'd worry that the baffles would tend to get in a bind when installing them if I was trying to count on the tapers matching. I'd rather just reduce the diameter of the left end and turn a little inside step in the right end for it to locate into.

I would shorten the blast space and use a Dater hole "Nice" solid plan.

Am I right that only the first baffle typically has a dater hole?

I'm still curious how accurate the length field on the Form 1 needs to be.

[daviscustom]

Just make sure your length on the form 1 is the same or longer then the finished can.

Don't know what the consensus is, but unless you are just wanting to do a compact can I would lean towards adding a baffle....less than 5" is pretty short compared to most of the better performing cans out there.

I assume you are going to go back and add the features on the front face of the K once you figure out the interlock?

[Capt. Link.]

Normally a rabbited edge is formed to mechanically trap the skirt between the baffle and the suppressor wall.This is a older design K type baffle but the same process can be used on newer styles.I think doing it this way makes for a stronger lighter baffle stack as the face is smaller and the cone shape is reinforced.

[punkinhead]

Bump. My tax stamp finally arrived so I'm back to thinking about this. I have a couple choices for 1" OD stainless tubing in my scrap bin - 0.065" or 0.049" wall. I plan on 28 tpi threads for the end caps which makes for about .022" deep threads. If I use 0.049" tubing this leaves 0.027" of meat in the tubing after cutting the threads. Just eyeballing it, that seems plenty strong so I'm leaning towards using the 0.049" wall tubing. Any opinions?

I'd also like to revisit the interlocking baffle thing discussed above. Is it really necessary for strength in a .22LR suppressor? It simplifies work holding in the lathe if I don't make them interlock (the OD will be the same at both ends of the baffle).

[Grounded]

Bump. My tax stamp finally arrived so I'm back to thinking about this. I have a couple choices for 1" OD stainless tubing in my scrap bin - 0.065" or 0.049" wall. I plan on 28 tpi threads for the end caps which makes for about .022" deep threads. If I use 0.049" tubing this leaves 0.027" of meat in the tubing after cutting the threads. Just eyeballing it, that seems plenty strong so I'm leaning towards using the 0.049" wall tubing. Any opinions?

I'd also like to revisit the interlocking baffle thing discussed above. Is it really necessary for strength in a .22LR suppressor? It simplifies work holding in the lathe if I don't make them interlock (the OD will be the same at both ends of the baffle).

I would go with the .049 but thread a 32 tpi @ .019 deep

[MCKNBRD]

Personally, I'd shorten that blast chamber up a little, maybe to 5/16" or so. It will help with FRP, and allow you to stack another baffle in there without adding too much length.

Pretty good plan, overall. I like the idea of the cone being supported by the face, but don't know the best way to do it. I've got an idea for my .22 can, but not sure how to explain it...think of a short (.065-ish) spacer at the end of the cone, with a matching shoulder on the outside of the next baffle face. I'll see if I can find anything that looks like it and link to it.

Byrdman

[57fairlane]

I second the face into the cone idea . . . if its just 22LR you won't have a problem but shooting .22mag or 5.7 through will oblong the cone hence sticking the next baffle in it to prevent that.

I say .049 wall if its just .22LR

[Baffled]

I guess I am in the minority - I'd make them full tube ID at both front and rear and slide them on in. There's just not that much pressure with .22LR.

With the same diameter both ends, the semi-finished baffle can be parted off, reversed, and then (as mentioned) held in a split tube, or even better, if a lathe is set up for it, a collet chuck like an extended brass "emergency" 5C collet bored to the tube ID and for the length of a single baffle. That sort of rig can also help when drilling holes... the baffle and 5C collet can be held in a square 5C collet block, and then held at an angle in a mill or drill press.

[whiterussian1974]

I guess I am in the minority - I'd make them full tube ID at both front and rear and slide them on in. There's just not that much pressure with .22LR.

I'm a Minority too! The gas bleed around the baffle OD will ENHANCE performance by pulling gas off boreline. Any minor jiggling inside the tube will siphon off energy by converting from velocity to vibration.
Many people don't understand the Mass Damped Spring Effects inherrent within suppressors. Compressible ideal gas, movable components, etc are all springs. Sadly many designers only think of metal spirals as springs and don't avail themselves of all the various materials and geometries that encompass the field of Spring Theory.
Even soap bubbles are springs!
Plus, what happens if the edges bind against each other? Can be fixed by removing and reinserting, but what if another baffle binds while you are fixing that one? Seems less hassle to maintain smooth sliding down tube.
BTW have you thought of having the cone mouth protude from the flat face? I termed these Alpha Baffles in my 1st Thread posted on this Site. One benefit is not needing to mill out a cupped circumferrence. It is integral if the mouth and throat insert 1/8-1/4" into the base of the previous cone.
Just some thoughts.

Oh, I almost forgot. Gorgeous design! I love that you included an sidewall to the endcap to give extra thickness to the blastchamber. This probably increases the outer tube's Hoop Strength by 300%. I don't know why ALL magnum suppressors dont incorporate this and an integral 2 chamber muzzlebrake into their endcap designs. Your's is for .22lr, imagine how much more benefitial it would be on a 65 kpsi cartridge?

PS: 6061-T6 Al for non-blast baffles. At such low P/T/V the system wouldn't benefit from stronger/denser materials. Some companies even use high density plastics for these baffles!
The pic CaptLink posted looks like the K's were hydraulically pressed into the tube. Unless you have a means of pressure forming the skirts around the faces, this process might not work for you and isn't needed for 160-400psi apps.
Your first series of pics in the OP are beautiful and should work wonderfully.
I would put 6.5"L on the Form 1. You can always go shorter. This gives you wiggle room and allows for workshop accidents or changes of mind. Maybe you will choose to telescope a 2"L of Reflex around the muzzle? If you Magnaport a pair of slits 1.5" behind the muzzle, this should give a slight improvement in the Precursor, and Uncorking dBs, but increase the blowby noise. Or enclose the chamber around the muzzle and this prevents added blowby and simultaneously lowers psi while increasing exhaust duration and lowering amplitude, which also further lowers discharge dBs.
In fact, nothing prevents you placing 12, 18, or 24" in the Length Field. Maybe you will decide on an integral or Full length Reflex in the 9-24 months it takes ATF to approve your F1.
Maybe it will take 10yrs if Hillary replaces Obama? Not being a troll, just watching the progression of anti-Constitutional encroachment by Politicos from BOTH Parties and ALL Branches of Gov't.

[punkinhead]

OK. I've shortened up the blast chamber to 5/16", I'll use the 0.049" wall tube, the baffles won't interlock, and I'll slide the last baffle into the end cap. Here's some screen shots:






I was curious how straight the inside of the tubing is so I turned a plug 0.004" under the ID by 1" long. It slid easily from end to end of a 12" section of tubing. I might drop the clearance down to 0.003".

I'll probably start cutting metal tomorrow.

[paul463]

OK. I've shortened up the blast chamber to 5/16", I'll use the 0.049" wall tube, the baffles won't interlock, and I'll slide the last baffle into the end cap. Here's some screen shots:






I was curious how straight the inside of the tubing is so I turned a plug 0.004" under the ID by 1" long. It slid easily from end to end of a 12" section of tubing. I might drop the clearance down to 0.003".

I'll probably start cutting metal tomorrow.

Looks like the one I did this past summer.
Some pics here; viewtopic.php?f=10&t=109728

[whiterussian1974]

OK. I've shortened up the blast chamber to 5/16", I'll use the 0.049" wall tube, the baffles won't interlock, and I'll slide the last baffle into the end cap.

I didn't read any reason in the posts why you should enclose the last K w the endcap.
It certainly keeps OAL down, but I would index/abut the endcap against the last K's skirt/base.
Removes any issue of binding the 2 together when assymbling.
Also, many cans have a nozzle on the far endcap to trap air around it, essentially making the endcap into a mini-cone.

[Dr.K]

OK. I've shortened up the blast chamber to 5/16", I'll use the 0.049" wall tube, the baffles won't interlock, and I'll slide the last baffle into the end cap.

I didn't read any reason in the posts why you should enclose the last K w the endcap.
It certainly keeps OAL down, but I would index/abut the endcap against the last K's skirt/base.
Removes any issue of binding the 2 together when assymbling.
Also, many cans have a nozzle on the far endcap to trap air around it, essentially making the endcap into a mini-cone.

I could see doing it to fulfill the length listed on the form1, and to squeeze an extra K baffle in there increasing suppression, .

[punkinhead]

I could see doing it to fulfill the length listed on the form1, and to squeeze an extra K baffle in there increasing suppression, .

That's the reason. My form 1 is 5-3/4". Kicking myself for not making it 6".

[whiterussian1974]

Me: "It certainly keeps OAL down, but I would index/abut the endcap against the last K's skirt/base.
Also, many cans have a nozzle on the far endcap to trap air around it, essentially making the endcap into a mini-cone."

I could see doing it to fulfill the length listed on the form1, and to squeeze an extra K baffle in there increasing suppression, .

That's the reason. My form 1 is 5-3/4". Kicking myself for not making it 6".

WOW! You sure didn't give yourself must wiggle room for calculation error, interrim design change, manufacture complications.
Let this be a warning to everyone filing Form 1s. ALWAYS add 2-4" to your planned build. It takes up to 24months to get an Approval if there is: Gov't Shutdown, DoJ Policy changes, Political effort to create artificial 2nd Amend Limitations, any "perceived" error in the App, etc.
There are cases where people filed for 8" can, then learned more about tech and wanted a full-length integral by the time F1 was Approved.
The Instructions say that you can go shorter, never longer.
It's a $200 lesson for some. Some people even get there F1 back in 90days and then didn't make the can for another few yrs. Imagine how much theory and application can change in that time.
Hopefully, that 1/4" won't harm your performance.
I've seen 2 other builds on this site that also nested the last K inside the endcap. They both turned out beautifully.
I'm sure you'll do a great job and gain valuable experience for future builds.

Here's a can that used the nozzled endcap I mentioned earlier.

[punkinhead]

WOW! You sure didn't give yourself must wiggle room for calculation error, interrim design change, manufacture complications.
Let this be a warning to everyone filing Form 1s. ALWAYS add 2-4" to your planned build.

Yep. I'm going to e-file for another one and be a bit more generous with the length. This one will work out fine though.

I started the first baffle this morning. I wanted to do one start to finish to understand the process and any special cutters or fixturing I'll want for the remainder.

Turn the OD and drill the bore:



I had to grind a special boring bar with a ton of relief to reach into that hole:









I'm going to make some aluminum soft jaws for facing and trimming to length after parting. This is a little close to the jaws for comfort.



I'm taking a lunch break now, then out to the shop for the mill work.