unsatisfactory results with first 22lr form 1

[T-Rex]

Hello all. I would like to say thank you to everyone whom regularly posts here. I've been reading as much as I could for the past year and a half. About 6 months ago I sent in my form 1 (4 to be exact, 2-.22 1-.223 & 1-.30). I received them back some time ago and just finished my first 22lr build. It did not end up as quiet as I had hoped. I have some form 4 cans so I compared it to my pilot and it wasn't close. It is hearing safe, but not as quiet as a CCI Std out of a 4.5" bbl and through a device should be.

I pretty much copied the X Caliber Genesis baffle design (not on purpose, but because of all the information I've learned). OAL is 5.625" w/ 6 baffles total. The blast baffle has 6 holes through the face leading into the outer chamber. First baffle is 17-4 and subsequent are 7075. 1" x 065, 6061 tube. Both the muzzle cap and end cap have a 60* countersink/cone pointing rearward. Bore is .27 throughout.

I fired 5 shots and you know a firearm is being discharged. Also, some flame/sparks are evident (in the dark) from the end cap. I didn't see this from my pilot. I disassembled the can to check gas flow. The level of dirtiness decreases towards the end cap with the last baffle being almost clean.

While dissapointed, I don't see this as a total loss. I see it as a $200 class in design and building. I might shear .06 or more from each cap to be able to add a wipe inside, maybe.

What improvements should be made on the next? Definitely going to add more baffles.

Again, thank you all for your help and much appreciated knowledge.

[ghostdog662]

May be a dumb question but you didn't put the baffles in backwards, right?

Any pics of what you made and measurements?

[CMV]

agree w/ needing pics.

I have 2 form1 .22's now and neither is anywhere close to 'perfect' from a design or execution standpoint. But both are nearly Hollywood quiet from a performance standpoint.

My takeaway from the experience is .22LR is fairly easy to suppress well.

I will say my K baffle can performs better on a pistol than a rifle. It is great on a 22/45 but I'd call it mediocre on a 18" rifle. So try yours on a long gun and you may be really happy with it??? Never know.

But if not, throw up some pics & measurements. I would bet there are some things that could be done to improve it w/o getting into remanufacturing.

[T-Rex]

I am having "issues" w/ my phone's camera, this morning.
I will post some later this evening.

Thank you,

[T-Rex]

Here is a drawing of the baffles. This is a working drawing and not all dimensions are correct, a few have been changed.



Here is the stack. Projectile path of travel is from left to right. I left it dirty to show gas flow.

[quietoldfart]

At a guess perhaps the front edge clip on each K baffle may take some of the blame for the suppressor not being so quiet as you'd hoped. In my early aluminum K baffles, each a bit over 1" long, I made slightly deeper vents than that after initially testing with no vents on the cones. My volume went up slightly. I have since gone to baffles about 0.55" long with a sloped rear section to allow deeper contouring of the baffle faces and a more perpendicular alignment of the cross-bore vents. Then I went a bit further and turned a groove into the outer edge of each face and turned down the cones to nest tightly into those grooves, shortening the stack enough that I could put an extra K into place in the same length of tube. The result is the quietest I've yet managed with my over-the-barrel hybrid design. Of course I wouldn't expect my results to be directly translatable to a screw on suppressor with no ported barrel to work with, but since that section behind the muzzle remained consistent throughout my experiments and the volume dropped quite a lot with both subsonic and SV rounds, it seems shorter K baffles work better. And nesting them together better still, with the ports deepened to place the line of sight between entry and exit ports at about 20 degrees. The conical shape of the rear section of each K helps with that more aggressive alignment, as it helps with a deeper face detailing which I feel helps in generating a strong toroidal swirling pattern inside each cone.

[T-Rex]

Thank you for your input and the pic.
So, your leaning towards the modified K baffle (X baffle) design.
I have one drawn up, extremely similar, with an OAL of .61". I think if I nest the rear, I can get it to your length.
Questions:
Is your vent drilled parallel to the bore but off centered?
How do you feel about my bore diameter and OD? I made the tolerance .012 overall to compensate for the addition of an anodized layer, throughout.
Do you use the X baffle as a blast baffle?

Thanks again.

[quietoldfart]

Is your vent drilled parallel to the bore but off centered?

The face vent is cut in with a ball end mill, run on my drill press with the K (X? these look more like a K to me, in cross section... where what most folks think of as a K baffle looks more like a sloped L to me) in an aluminum jig to maintain position, parallel to the bore. The same 1/4" ball end mill was used inside the cones, but with the jig tilted about 10 degrees so that the mill bit is going outwards, carving away from the bore at that slight angle. And I cut them in 2 steps, first closer to the bore with 1/8" of the bit cutting the initial hole, then sliding them out about a further 1/16" or a little less and plunging a second time to open out the vent a little. Measured along the bore the bottoms of the two round-bottomed holes are staggered a little over 1mm. A 1/8" drill bit can go right through both vents, but they're not drilled through in such a way so a 1/4" bit will not go through all the way. This is the steel initial baffle.

How do you feel about my bore diameter and OD? I made the tolerance .012 overall to compensate for the addition of an anodized layer, throughout.

I initially used 0.25" for each baffle and the front cap, but have recently opened it out to 17/64", or 0.266" approximately, as I was having slight baffle rubs which showed up on low velocity CCI Quiet (about 570fps in my pistol) rounds when recovered from putty. Not CCI standard velocity (which go through my ported 7" barrel at about 925fps) which show no sign of strikes. Instability I suppose, as alignment looks good. Anyway, your 0.27" should be fine if the suppressor shoulders accurately.

My OD for the baffles is about 0.865" while my tube ID is 0.870", so clearance of 0.005". When clean the baffles drop in or out easily. When I've shot a couple of magazines it gets a little bit gritty, so I made a baffle puller by brazing a 1/4" hemisphere of steel to the end of a coathanger wire with a loop brazed into the other end. Pushing that to the end of the stack and shifting it slightly to one side enables pulling the 7 baffles out easily. I suppose if I weren't so fussy about cleaning frequently and shot a few hundred rounds it might become quite difficult to use such a baffle puller... but a push rod would probably still work from the rear of the suppressor. I'm unlikely to be that careless however. And I assemble with white lithium grease lightly glazing all baffles if I intend to shoot more than a handful of rounds in succession. That makes if VERY easy to extract them. Doesn't seem to have any effect on sound level, it being just a light film.

Do you use the X baffle as a blast baffle?

When first making it a 7 baffle can I used all the same 7075 Al, but later I installed a mild steel initial baffle with a deeper-still face profile and slightly thinner cone walls, facing off the initial entry point about 0.10" to give the gasses a little room after the muzzle. I've also re-crowned the barrel with a deeper countersink and polished that, likewise to give gasses more space to expand before the first K. I don't use a blast chamber spacer. Being an OTB design there's no need for that. If it were a muzzle-mounted suppressor with no OTB volume I'd probably use a 0.50" or slightly longer blast spacer, and perhaps a contoured but non-vented blast baffle with a Dater hole. Different dynamics and pressures between the integral and front-only suppressors.

[T-Rex]

I understand.
What components are missing from the pic in your first post?
Are all interior angles equal?
What are your thoughts on less baffles creating more volume vs slightly less volume w/ more turbulence (same, net volume tube)?

Your ideas are valued and learned.

[quietoldfart]

What components are missing from the pic in your first post?

Here, sorry to hijack the thread a bit, but here's the original thread I started to show off this evolving suppressor:
viewtopic.php?f=10&t=122425

Are all interior angles equal?

Do you mean are the inside and outside of the cone parallel? Yes. Or what angles if not those?

What are your thoughts on less baffles creating more volume vs slightly less volume w/ more turbulence (same, net volume tube)?

Seems likely there is a maximum number of smaller baffles beyond which diminishing returns transit into a reversal of efficiency. But I've not found that limit with these tiny baffles. My small K's are far from alone in this field, as a fellow in NZ recently showed with his micro K can for .22" and a number of others have demonstrated. I've tried ~1.25 long K baffles with about 0.25" waists parallel to the bore. I think the necessarily greater distance between ports makes these relatively inefficient. The angles are also less than ideal for trapping sound/pressure, in my opinion.

[T-Rex]

All questions answered, thanks.
I have to admit that I've read that post in the past,maybe twice.

Thank you, again.