To Subscriber - Gamo Urban moderator insert similar to the Notos insert

[naptemp]

Subscriber, you have made a fantastic moderator insert for the Umarex Notos.
I have 2 Notos and both have your insert.
I really thank you for that.

The Gamo Urban has a similar moderator (permanently glued to barrel) with an insert attached with 2 pins just like the Notos.
The same (permanently attached) moderator is used on several other Gamo and BSA airguns.

The Gamo Urban has been sold for many years and yet no satisfactory moderator appeared.
Unhappy people will just remove the original moderator by any means they have.

Subscriber, I am asking you really nicely if you could make a moderator insert for the Gamo Urban.
Let me know if I can help.

[subscriber]

John,

Considering that I check this gate sporadically, your post makes an interesting alternative to a PM

I would need the interface dimension to do an Urban specific design.  Removing the stock baffles and measuring their features would help.  The cavity in the casing should also be measured as it will be larger than the insert.  Diameter and depth, with some idea of the internal shape (pictures).  Pictures of the stock baffles too.

Diameters should be measured at a number of places around the part (because they are not actually round).  Also, the retaining pin size and locations relative the the front face of the casing; and relative to the front and rear "shoulder" features of the stock baffles.  The spacing of the retaining pins around the center is obviously also rather important.   The more accurate the measurements the better.

 You can't have too many features measured, but you can have too few.

I no longer get GTA forum update notifications, for unknown reasons.  So, I will check back here next week.  PMs still seem to work, with notifications.

I assume you want an extended moderator, like the one you have on your Notos?

[naptemp]

Subscriber,

Thank you for your reply.

I have just bought a Gamo Urban and will be a while until I receive it.
I used to have one but sold it.

At the time I have printed this insert which fitted perfectly: https://grabcad.com/library/gamo-urban-baffle-core-upgrade-1
That insert reduces the noise somewhat, but I think it is too short.
I think you could the measurements from the stl file above.

An extended moderator for sure.
The quieter the better.

Once I get the Urban I can send the measurements.

This is how the baffles look.

[subscriber]

Thanks John,

The length of the "body" (without the stem) measures 115+ mm from the STL.  That is rather short.

I may be able to core out the STL after converting it to a Solidworks part.  Then extend it a similar length I used for the Notos muffler; and populate it with my own baffle design. 

But, where does the barrel go, relative to that "stem"?  What is the stem's function?  The Urban front end image does not help answer those questions.

Are the rectangular slots at the front where the retention pins fit?  See image with red lines below.  If so, then those features have to stay.  It would be helpful to see the cavity this insert fits into to extend it intelligently.

My opinion of that STL design is that it has too many baffles, too close together.  That the baffle walls are too thick; and that these factors combined reduces the expansion volume excessively.

[naptemp]

Thanks John,

The length of the "body" (without the stem) measures 115+ mm from the STL.  That is rather short.

I may be able to core out the STL after converting it to a Solidworks part.  Then extend it a similar length I used for the Notos muffler; and populate it with my own baffle design. 

But, where does the barrel go, relative to that "stem"?  What is the stem's function?  The Urban front end image does not help answer those questions.

Are the rectangular slots at the front where the retention pins fit?  See image with red lines below.  If so, then those features have to stay.  It would be helpful to see the cavity this insert fits into to extend it intelligently.

My opinion of that STL design is that it has too many baffles, too close together.  That the baffle walls are too thick; and that these factors combined reduces the expansion volume excessively.

Unfortunately I do not remember how the moderator looked internally.

I think we should wait until I receive my new Gamo Urban (around beginning to mid November).
Then I can provide you with detailed dimensions and photos.

[subscriber]

Sure.

The other detail I need is the outside diameter of the stock moderator body.  My intent is to match its OD, so the added length does not look odd.

[subscriber]

I got curious so I compared the Urban STL design you linked above, with my Notos extended insert - images below.  (the Notos insert version with O-ring grooves was at the top of my file list, so I grabbed that one). 

[naptemp]

I printed your Notos insert with orings and it works very well.

Your Notos insert and the Urban insert do look similar, but the Urban seems to have too many baffles.

I will send you detailed dimensions once I receive the Urban.

[subscriber]

In the meantime, the video below shows how to get the stock baffles out.

I see that the pin holes in the front cap are round.  It would be very good to know the diameter and placement of those pins.  Presumably, the pins sit in the rectangular cut-outs near the front of the STL you pointed at.  Probably right in front of the stock rear insert shells.

I have copied the STL's cut-outs but they will not be able to print unmodified with my extended nose insert design, due to the overhangs.  I would much prefer to close that space in, leaving round or oval holes for the pins.  But, I need more information about the pin placement:

If you tap the pins so they stick out perhaps 1/4" you should be able to measure over the outside of the pins.  Then by subtracting one pin diameter you will have the pin spacing distance.  Along with the pin diameter will design printable holes, with smaller internal bosses than I have now, around the rectangular cut outs. 

As you can see from the attached images, my design does not have the stem, nor the shoulder the stem grows from.  My design will use the front shoulder to limit how deep the insert goes into the stock cavity.

I copied the OD of the STL at  28.43 mm (away from the wings).  I would like to know the diameter of the cavity, perpendicular to the "wings"; and near those grooves, but no in them.

The baffle design is essentially the same as for my Notos extended insert.

Jump to 3 minutes 45 seconds for pin removal:

[naptemp]

I also only get alarms for personal messages not thread posts.

I will have my new Gamo Urban in about 2-3 weeks.
When I get it I will send you all the dimensions you ask for.

I am sure that there are hundreds of Gamo and BSA PCP owners stuck with Gamo's ridiculous moderator.
That was my main complaint about the Gamo Urban, which was also my first PCP, and really accurate with cheap pellets.

I agree that it would be much better having holes instead of cutouts for pins.

By the way, the outer moderator shell has holes in it (front left and right of the moderator) and you can see the red baffles from the outside.

[naptemp]

The designs you posted look very similar to the Umarex Notos insert.

By the way, the Gamo Urban is capable of significantly more power than the Notos and all the noise that comes with the power.

Can you have a design which is a little more quiet?
I assume that means more silencer volume.
Maybe, a wider or longer extension.
I personally do not mind having a wider moderator.

[subscriber]

John,

I can make the insert longer and wider.  The insert section is already a little wider than the Notos' insert.  But the length and baffle structure are the same.  If you tell me how much extra length and width you can tolerate, or want, I will do the design over to utilize that.  Best to start with the internal and external dimensions of the stock casing.

The vents in the stock Urban casing may be why the Urban is louder than you expect.  There is a reason why the perforated tubes in an engine muffler are inside a closed casing.  I have ranted and railed against moderator and shroud vents a number of times.  No need to do it again, here.  Except to say that any number and size of side vents that have enough combined flow area to make the report as measured from the font quieter, will make the report louder as measured from the side and rear.  I assume the idea is to make it quieter than stock from all sides 

[avator]

In the unfortunate event I ever destroy the "pickle" on my Urban I will opt for the full shroud mod.
I'm lucky enough to be in a situation that the sound of shooting is an issue. Matter of fact, gunfire is a form of music around here. I just think the Urban looks great with a full shroud.

[subscriber]

Shrouds look better; yes.

[avator]

That was not meant to downplay your inserts or baffles. I think you are doing a great service for members looking for those options. Like I said.. loudness is a non issue for me and I prefer the clean look of a shrouded gun.... not enough to replace the factory "pickle" though. I don't find it as offensive to the eyes as some others seem to. It looks much better than some of the "soup cans" that some are paying top dollar for.

[subscriber]

Bill,

I happen to agree with you about not liking the snake that swallowed the rat look.  Or drawing attention where a shroud would not.  I own nothing with pickles, but that does not stop me from designing inserts for people that want to improve theirs.

If my previous reply seemed short, it was because I am not officially awake yet.

[naptemp]

I have received my new Gamo Urban and took many photos (see attached) and measured dimensions.

These are the dimensions in millimeters.

External tube
Length from end of tube to the internal barrel structure (seen in first photo): 122mm
Outer diameter: 37mm
Inner diameter: 32mm

Internal Baffle
Small outer diameter: 29mm
Large outer diameter: 32mm
Total Length: 147mm
Outer diameter of the small end: 12mm
Length of the small end: 30mm

Pins
Outer diameter: 2.2mm
Length: 22mm

[naptemp]

John,

I can make the insert longer and wider.  The insert section is already a little wider than the Notos' insert.  But the length and baffle structure are the same.  If you tell me how much extra length and width you can tolerate, or want, I will do the design over to utilize that.  Best to start with the internal and external dimensions of the stock casing.

The vents in the stock Urban casing may be why the Urban is louder than you expect.  There is a reason why the perforated tubes in an engine muffler are inside a closed casing.  I have ranted and railed against moderator and shroud vents a number of times.  No need to do it again, here.  Except to say that any number and size of side vents that have enough combined flow area to make the report as measured from the font quieter, will make the report louder as measured from the side and rear.  I assume the idea is to make it quieter than stock from all sides 

I have added photos and dimensions.

The insert may need orings, like the Notos insert.

The insert can be both longer and wider.
For wider, I assume that there will be a small taper to the larger width.

These can be a starting point, and you can pick dimensions if you want:
10cm length in front of barrel
5cm width
2-3cm length of taper

[subscriber]

Thanks, John

There seem to be 11 image files, but they do not all display.  Photoshop does not want to open them either.

I will see what I can make of the info that is clear, this evening.

[subscriber]

I just tried renaming the extension from jpg to jpeg and it worked on the file where I tried it!