M22 x 1 mm threaded mufflers for the Airacuda Standard

[Robert 5mm]

"M22 x 1 mm threaded mufflers for the Airacuda Standard"
The 22 Airacuda Standard does not come with a 1/2 20 muzzle adaptor, so I asked for a custom muffler design that screws directly into the shroud from one of our GTA members - Subscriber.  I had previously acquired with the help of another GTA member Torquemaster – a Subscriber designed LCD for the Avenger, a shorty and a long. Both are very nice and do the job on my .177 and .22 Avengers.
Due to my request, the first design was just for a 1" OD x 6" long muffler, but during the redesign I asked for a 1” and a second 1.5” OD x 6”. The redesign occurred because I initially messed up and stated the thread size to be M18x1 – but these guys corrected my error and the design was changed to M22x1 with 18 mm depth.
They sent me an amazing four muffler versions to evaluate; including two internally different 1.5" OD versions, a 1.25" OD and 1" OD version.  These were designed by GTA member Subscriber, and printed by member TorqueMaster. I got a whole lot more than I asked for.

These were my initial impressions: ( After this I added a “Sound Meter” app to my Galaxy Tablet )
By Ear with no pellet and I did not want to try with pellets for safety reasons:
1 = lowest - 10 = highest Relative to my ear up next to muzzle.
The stock internal baffle stayed in place for all 5 tests.
Stock baffle alone Sound level of 10
1.5 Model "A"  Sound level = 2.5
1.5 Model "B" Sound level = 2
1.25 Model "D" Sound level = 4
1.0 Model "C" Sound level = 5
The mufflers all decreased the relative sound level in my opinion.
And none of mufflers restricted my Foster quick attach adapter to my compressor.

Next I tried to test using my Galaxy tablet with the Sound Meter app - set 10 feet to the side of the muzzle.
This app on my tablet is not a proper sound meter and my testing results varied greatly producing worthless data. From the ear testing model B was the best in my opinion, but all were better than stock.
Sorry I do not have any group sizes, my gun developed a PSST leak during the sound testing and I did not get to shooting for accuracy and no clipping seemed to occur. The gun was displaying inaccurate results on my Chronograph, so any data would be questionable. This may be related to changing the rotary knob from Max to Min and back numerous times.
Please see attached pictures

[subscriber]

If anyone is interested in printing their own, the STL files for three of these designs can be downloaded here:  https://www.gatewaytoairguns.org/GTA/index.php?topic=209681.msg156469202#msg156469202

As 1.5" OD model "B" performs a little better than 1.5" OD model "A", the STL for model "A" is not included in the zip file at the above link.  The difference in performance is due to different baffle shape.  Something TorqueMaster and I predicted, then confirmed by Robert 5 mm.

[JayDee24ca]

I have been searching for a m22x1 to 1/2 x 20 adapter for my Aircuda Max. No one apparently has a ready made solution. Do I understand correctly that I might be able to buy one from you?
JD

[subscriber]

John,

Such an adaptor is not what we devised.  The above are LDCs mount directly to the air rifle shroud, without needing the adaptor you seek. 

In theory, I could design such an adaptor, but it would be weak when made from plastic, with the 1/2" stud having a "large" hole through it.  This part really should be made from metal.

Other Airacuda models do come with the M22 x 1 to 1/2 20 aluminum adaptor, so you might contact the manufacturer, JTS.

You can get the adaptor from Donny FL.  I found it listed on Krale, but I am sure you could contact other suppliers:  https://www.krale.shop/us/moderator-adaptor-donnyfl-jts-airguns-evanix-rainstorm/

Another potential source would be aliexpress: https://campaign.aliexpress.com/wow/gcp/tesla-pc-new/index?UTABTest=aliabtest377151_530968&src=google&aff_fcid=e59291b597c64ebb9975178ac0ce43d0-1692064201362-09187-UneMJZVf&aff_fsk=UneMJZVf&aff_platform=aaf&sk=UneMJZVf&aff_trace_key=e59291b597c64ebb9975178ac0ce43d0-1692064201362-09187-UneMJZVf&terminal_id=34216ccd899b4b4d86f732a5534cad77&wh_weex=true&wx_navbar_hidden=true&wx_navbar_transparent=true&ignoreNavigationBar=true&wx_statusbar_hidden=true&bt_src=ppc_direct_lp&scenario=pcBridgePPC&productId=1005005253102441&OLP=1085100208_f_group2&o_s_id=1085100208

[JayDee24ca]

Thanks for that, you are right that metal would be far superior. I will try JTS to see if I can get one, thanks again.

[jusanothajoe]

You can get that adapter directly from Donnyfl.
Just be aware, Airacuda Standards are known to have clipping problems with a moderator installed, mine does.
https://donnyfl.com/collections/adapters/products/evanix-rainstorm-1-2-x-20-unf-adapter-a29

[subscriber]

Derrek,

That suggests the smart thing to do would be to use a .25 moderator on a .22 Airacuda, to provide extra clearance.

Pertinent info:

Moderators, drill bits and shrouds

As I already posted, the Buck-Rail moderator I put on the MAX was canted up and to the right about 4° and was clipping BAD! I had mentioned this to Travis and he suggested that I turn the shroud around and try the other end (DOUGH!  ).

I removed the barrel band, adapter, end nut, inserts, turned the shroud off and turned it around, reassembled the whole thing and remounted the moderator, loade up a couple mags, took aim and still had a wandering POI. 

I was going to shoot Chris at Bick-Rail an email asking him about the POI when I noticed he had already shot me a reply about another issue and reminded me that they make the passage a little small and it may have to opened up some to keep some guns from clipping.

I chucked up a 6mm bit and reamed the hole out, blew out all the curls, remounted the mod and now the POI is stable. 

Next up: Trigger massaging 

[Robert 5mm]

I also have the .22 JTS Max model with a JTS 1/2 x 20 adapter included and I have a Buck Rail moderator installed.
It does not have any clipping occurring.

The JTS Standard did not have any clipping that I noticed while doing the sound testing, but I also was not shooting groups.

Buck Rail also sells the DonnyFl 1/2 x 20 metal adapter for the Standard.
https://buck-rail.com/product/jts-airacuda-evanix-rainstorm-threaded-adapter/

But the shroud mounted Subscriber designed muffler eliminates the need for the adapter ( but metal is better than plastic )

[subscriber]

The greater the uncertainty about coaxial mounting or angularity, the larger I specify the bore and the more taper I use towards the front.  The image below shows what dimensions I used for Robert.  If one can see obvious angularity on the mounted device, that degree of bore clearance would not be enough. 

I used angular lines that describe a shallow cone, having an ID of 8 mm at rear end, and a ID of 9 mm at the front end; over the 152 mm functional length.

Bear in mind that FDM 3D printing of a nominal 8 mm hole would typically close the hole diameter by around 0.3 mm from the CAD value.  So, the "8 mm" rear end bore would print 7.7 mm.  That is just over a 1 mm radial clearance with a .22 pellet.  At the front end, that radial clearance grows to 1.5 mm.

[jusanothajoe]

Derrek,

That suggests the smart thing to do would be to use a .25 moderator on a .22 Airacuda, to provide extra clearance.

Pertinent info:

Moderators, drill bits and shrouds

As I already posted, the Buck-Rail moderator I put on the MAX was canted up and to the right about 4° and was clipping BAD! I had mentioned this to Travis and he suggested that I turn the shroud around and try the other end (DOUGH!  ).

I removed the barrel band, adapter, end nut, inserts, turned the shroud off and turned it around, reassembled the whole thing and remounted the moderator, loade up a couple mags, took aim and still had a wandering POI. 

I was going to shoot Chris at Bick-Rail an email asking him about the POI when I noticed he had already shot me a reply about another issue and reminded me that they make the passage a little small and it may have to opened up some to keep some guns from clipping.

I chucked up a 6mm bit and reamed the hole out, blew out all the curls, remounted the mod and now the POI is stable. 

Next up: Trigger massaging 

My Airacuda Standard is a .25, my moderator is a Donnyfl Sumo .25, I drilled it out to .375" before installing.
I haven't visually proved mine is clipping, but accuracy goes south when installed.

[subscriber]

It sound like one should face the shroud square in a lathe, or at least verify it, before reaming out an expensive LDC.  That said, .375" for a .25 sounds about right in the first place.   If there is obvious angularity, more than a .375" bore would seem to be indicated.  Perhaps using a taper pin reamer of some sort.

If the shroud threads are cut off axis that would make the problem more difficult to fix.  If there is sufficient clearance between threads, then the squared shoulder should dominate; but the bores may not be completely coaxial.

Advice from Travis I quoted above, was to flip the shroud tube over, and to use the other end at the front, in case it is better.  Advice I would suggest to Travis, is to get on the manufacturer, to be more careful when machining the shroud tubes...

[jusanothajoe]

I tried once to get the shroud off with no heat and it wouldn't budge.
I will try again with heat and if successful, I will true up both ends in a lathe and re-install.
But after talking to Travis, he isn't 100% sure that will fix it, but worth a try.

IIRC my Sumo was around .300 to start, so I didn't have to take out much to get to .375

[jusanothajoe]

Took my donny Sumo apart and found it was barely clipping the end cap.
I opened up the end cap about 1/16 put it back on and accuracy returned.
If this hadn't worked, I was going to remove the shroud and square up the ends in a lathe.
I'm not counting on a fix for this from JTS, especially for the Standard.

[subscriber]

Derrek,

Opening up just the front end bore is a smart move.   Due to the nature of angularity, the front end of an LDC is at highest risk for clipping.  So, here is a bit of diagnostic advice that hinges on that principle:

If you or anyone else wants to see how close to clipping your setup is, try this trick, shared by GTA member TorqueMaster, along with his pictures:

1. Apply masking tape to the front end of your LDC, with your PCP unloaded and the action open.  You can press the tape firmly along the hole edge to "emboss" it and make the hole edge and center more obvious.

2. Shoot one wadcutter to cut a clean hole in the tape.  Observe how far off center the hole is compared to the bore of the LDC; and in which direction. 

3. Do this two or three times with fresh tape to see if it repeats.

4. You can shoot more shots through the same piece of tape to see if the hole pellet grows; but need to endure the tape does not blow off, or shift after each shot.

5. You can also remove the LDC between shots to see if reinstallation affects alignment.

6. If the hole in the tape is near the inside edge of the front bore, then you likely will see clipping in the future.  Clipping may be intermittent in a marginal case.

7. After diagnostics and intervention, repeat the tape test to see if the improvement looks satisfactory.  Ideally, the hole in the tape will look like it is in the middle of the LDC bore, when viewed from the front and "sighted" from behind.  In other words, any misalignment should be so small as to not be obvious by eye.


The second image is a view down the bore of the removed LDC, "sighting" the hole in the tape from behind.  It shows a lack of concentricity in that instance, but with functional clearance.