Author Topic: .22 Marauder 32 mm OD x 140 mm LDCs - Direct shroud mount; and 1/2-20 (Read 1689 times))

subscriber · « **on:** November 27, 2023, 05:37:14 AM »

GTA member jolofree asked about a muffler for his Marauder:
https://www.gatewaytoairguns.org/GTA/index.php?topic=182738.msg156492161#msg156492161

I made some suggestions, and what panned out was this: A 32 mm OD x 140 mm long 3D printable LDC in two versions. One version has a 13/16-28 male thread, and is intended to replace the stock Marauder shroud front endcap. The other version is identical in all aspects, except that it has a 1/2-20 female thread.

The latter version would require a thread adaptor to replace the stock front shroud endcap; such as this one: https://donnyfl.com/products/marauder-mrod-1-2-x-20-unf-adapter-with-thread-protector

After thinking about what jolofree had asked about keeping his stock Marauder baffles, I decided to design only an external add-on. At first my thinking was that integrating the internal shroud baffles into the external muffler would better align the parts. But keeping them separate would keep the platform closer to stock.

Using the DonnyFL adaptor might be the more robust option with respect to the thread, but the direct mount might be the cheaper option. I might even suggest getting both.

Both STL print files are attached in the same zip file, below. The parts need to be positioned with their threads uppermost on the printer platen, to print the cones inside correctly. Anyone is welcome to print these parts for themselves or anyone else. I have confidence that the 1/2-20 thread will be usable directly off the printer; but the 13/16-28 thread may require some iterations to get it just right.

If you are unable to print these parts for yourself, and don't know anyone that can print them for you, I can recommend someone.

subscriber · « **Reply #1 on:** November 27, 2023, 06:30:13 AM »

In case you want to print just the 13/16-28 male thread to prove it good first, here is just that aspect as a part STL:

jolofree · « **Reply #2 on:** November 27, 2023, 09:21:11 PM »

Yes Sir, These designs look great. The size is perfect.
I have ordered the adapter from Donnyfy, the threads on it are 1/2"-20 so I will need the design with the female threads to match that.
Could you please advise how to best contact Bob or Mike to get this done?
Also I was advised by a member on Air Gun Nation to look into installing t 'Depinger' in the Marauder.
I'm not sure exactly what that is, where to obtain one, and how to install it.
Do you think that would make the Marauder have a quieter shot signature?
Thanks, I really appreciate all your help with this. j

subscriber · « **Reply #3 on:** November 27, 2023, 10:43:50 PM »

John,

The 1/2-20 adapter is more versatile for any future bits you might want to try. So, good choice.

You can PM Bob and Mike here:
Bob: https://www.gatewaytoairguns.org/GTA/index.php?action=pm;sa=send;u=67950
Mike: https://www.gatewaytoairguns.org/GTA/index.php?action=pm;sa=send;u=19269

A depinger goes into the airtube, so to install it you must depressurize the airtube first. Failure to do that is likely to throw the front cap of the airtube (the one with the foster fill fitting on it) forcefully enough to cause damage or injury.

Depingers come in many forms. Some are a partition in the airtube with a small hole in it. This is a flow restrictor placed about midway in the airtube to damp pressure waves that bounce in the airtube on the shot. Others are an actual bottle brush that does the same thing. Installation instructions are included with the depingers that are sold.

Depending on when your Marauder was made, it may have Crosman's version of a depinger. Anyway, what they are, how they work, and how to install them is covered by many threads and posts. This google search string points to such posts on GTA:
https://www.google.com/search?q=site%3Awww.gatewaytoairguns.org+depinger+marauder

And yes, if your Marauder does not have a good depinger, it will be making a loud pinging sound on every shot. That is, if it is a stock unregulated version. Marauders were available with regulators from Crosman to keep the velocity more constant over so many shots, but at a lower power level than the unregulated ones. There, the regulator acted as a depinger, but if yours lacks a regulator, then a depinger will help reduce the noise.

subscriber · « **Reply #4 on:** November 28, 2023, 02:00:18 AM »

John,

You had a question about the "front barrel mount drilling" on AGN. Drilling it out to flow more air tells me that the person suggesting that modification was referring to the air stripper/diverter; that is pressed onto the muzzle end of the barrel. This part:

Here is a discussion about drilling out the vents on the Marauder air stripper - although I think one does not need to go quite that large on the holes: https://www.gatewaytoairguns.org/GTA/index.php?topic=42482.msg396424#msg396424

subscriber · « **Reply #5 on:** November 28, 2023, 02:06:08 AM »

This one is nicely done:

jolofree · « **Reply #6 on:** November 28, 2023, 05:44:39 PM »

Yes that's it. I think I'll give that mod a try. Thanks!
And I cant srr sent messages, Did you receive my message about the shroud threads?
They are 8mm or .315" and virtually the same maybe one more thread in the shroud.
JF

subscriber · « **Reply #7 on:** November 28, 2023, 11:19:31 PM »

John,

I just saw your PM about the shroud endcap thread length being 8 mm. I have updated the moderator thread length and the thread test piece. Version 2 STL print files with 8 mm long threads are attached below:

rualert · « **Reply #8 on:** June 10, 2024, 10:56:05 AM »

Hey Subscriber, toyed around with these for the Marauder Pistol yet? That could be quite useful as many have added an extension to reduce the report.

Casey

subscriber · « **Reply #9 on:** June 10, 2024, 11:09:20 AM »

No, Casey, I have not.

Care to be more specific?

rualert · « **Reply #10 on:** June 17, 2024, 11:09:04 AM »

Yes, I was wondering about a shroud mount extension for the P-rod. I am not up to speed with the design side of printing, but I currently run both a pair of FDM printers and a resin printer. I can get you more specific measurements if you don't have them. I have printed both your M-Rod extension which works fantastically and showed a 5 -6 db reduction on my 25 making it even more friendly.

Casey

subscriber · « **Reply #11 on:** June 17, 2024, 11:16:05 AM »

The important detail is the thread designation: Diameter and pitch.

I assume perhaps incorrectly that the moderator for the PROD should be smaller than that for the MROD? Please advise, unless you want to leave that up to my discretion. OD and length (or range of dimensions) you are looking for .

rualert · « **Reply #12 on:** June 18, 2024, 03:02:13 PM »

Okay, sir, it looks like from my thread gauges and caliper that it's a .68" diameter 24 tpi SAE for the threaded part of the original shroud end cap. Its outside diameter is .75" and the depth of the threaded side to engage in compression on the factory baffle stack is .36". I have attached a couple of pictures. As for sizing, I am experimenting with your LDC Bore Clearance Study pieces, and that diameter is fine in my opinion. Perhaps a simple endcap to 1/2-20 adapter to provide the proper host fit. If you feel up to it perhaps also a complete thread unit like the above in the same 1" diameter for those who would prefer a complete one-piece solution as well.

Images:

Thank you,
Casey

subscriber · « **Reply #13 on:** June 18, 2024, 07:23:47 PM »

Thanks, Casey

subscriber · « **Reply #14 on:** June 18, 2024, 10:29:07 PM »

Casey,

I design two variants of .22 PROD LDC. Both have an OD of 1", and are 4" long ahead of the shroud, after mounting. One version is cylindrical; while the other tapers up from 3/4" at the very back end, to better match the shroud OD. Internally, they are identical. See attached images below.

The attached ZIP file contains the STL for both cylindrical and taper LDC versions.

Note that you need to rotate the part in your slicer, so the threads are uppermost - see last image. Else internal baffle cones will be unsupported; and the part unusable. Print at 100 % infill, with all supports turned off.

I suggest that you first verify the thread fit by printing just the rear inch or so, using the cylindrical version for a broader connection to the platen. If the threads are too tight, use the slicer to scale the part to 99.5% in the X and Y axis. Leave the Z-axis at 100%, or the pitch will be off and cause the thread to go over-tight before fully screwed in. If the thread is too loose, print the X and Y axis at 100.5%.

I expect the thread to screw in somewhat tight the first time, and then loosen up after that to a just snug fit. This is when printing the STLs directly, without scale adjustment, although it depends on you printer, material, slicer and settings. So yours may or may not need intervention.

rualert · « **Reply #15 on:** June 19, 2024, 10:45:10 AM »

Thank you kindly, sir, I will get them printed and provide feedback as soon as I can test them out. I appreciate your time and assistance, sir, it's great to find others who think alike.

Casey

P.S. I have had great success with your designs and my printer,slicer, and settings seem to be right on point thus far. Again I will provide feedback as soon as I can.

subscriber · « **Reply #16 on:** June 19, 2024, 09:49:09 PM »

Casey,

In case you find the threads on the above version of LDCs too tight, you might try Version 2. Version 2 has more relief in the threads, intended to screw on easier.

If you have not yet started printing the first version, I might suggest you try version 2, first.

ZIP files contains version 2 STLs for both taper base and cylindrical LDC versions.

Image below is of superimposed thread profiles, for V1 and V2; to show where material has been removed from thread-form:

rualert · « **Reply #17 on:** June 20, 2024, 09:28:57 AM »

I will try v2 of the tapered extension. I have however already printed and tried v1 of both. I forgot about the pull-off fill cover, so the tapered version is best for those who do not wish to unscrew their extension to refill. That said both screw on smoothly and tighten as expected. I used .16mm and .12mm print modes to check and see if I needed the additional quality/precision of the .16mm print level. The .12mm is fine and saves a bit of time, I may try .2mm to speed things up a bit more. Both versions of the extension, tapered and straight quell the last bit of pop exceptionally well for a short 4-inch extension. I am more than pleased with the results and would recommend these to anyone wanting just a bit more quiet from their Marauder Pistols/Carbine. Perhaps we should create a new post to share with more of our air-gunning brothers and sisters.
Picture of the tapered model:

Thank you again, and I'll get a v2 printed to test for you as well.
Casey

rualert · « **Reply #18 on:** June 20, 2024, 01:07:02 PM »

A couple more things. I will perform some actual DB testing with and without the extension to get a rough number for those interested. I will also shoot a couple of groups with and without to see if any difference is visible in group size and POI. More to come.

Casey

subscriber · « **Reply #19 on:** June 20, 2024, 06:29:09 PM »

Thanks for the feedback, Casey

I am glad that the fuller thread-form versions works for you. I expect that then the V2 might screw on with some play at your print settings. Even so, they might help someone struggling with Version1.

Your results make me wonder about the print settings John is using in this thread:
https://www.gatewaytoairguns.org/GTA/index.php?topic=209016.msg156539630#msg156539630

Feel free to start a thread in the PCP gate about your PROD, posting your results and impressions of this LDC. Post a link to the section of this thread where the PROD LDC project starts:
https://www.gatewaytoairguns.org/GTA/index.php?topic=211473.msg156539885#msg156539885