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Umarex Notos CRK Review

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Martin_T:

--- Quote from: subscriber on April 05, 2023, 02:01:59 AM ---The images below show my best effort at extended inserts (similar to what Dave tested) designed to fit the unmodified Notos "can". 

I scaled the retention pin positions from the images in this thread, and applied a human trait:  When there is no clear reason to choose fractional dimensions, most designers default to full units.  So, the pin to pin spacing seems to land 8 mm away from the centerline, and thus 16 mm center to center, placed in the 32 mm OD casing.  I did something similar for the pin placement from the casing shoulder.

You may need to sand down the rings I added to the insert OD to ensure it is not loose in the casing.  The rings are 0.002" taller than the surrounding OD, so not very aggressive.

The pin holes should print close to 2 mm in diameter.  You may need to chase them, but decide that after fitting the insert OD to the casing ID.

The STL print files are attached, below.  One for the long snout version; the other for the short snout. 

Both inserts will have a cavity ahead of them that Umarex designed as primary expansion chamber, ahead of the muzzle.  The difference between the inserts is how far the pellet has to travel in that primary chamber before it is shielded from turbulence by the first air stripper.  Will there be any meaningful grouping ability difference between the two versions?  I hope someone prints either or both to find out.

This may be my last contribution on this topic for 5 weeks.  I am going walkabout in the Southern hemisphere, imminently.  I need to do my taxes and a few other things before I am ready.

--- End quote ---

As I recently got me a Notos as well, (been eyeing it on and off for the last 6 months, and when Ted endorsed it, I finally gave in!) I found this thread in my search for info on mods on the Notos. So I want to thank both Firewalker and especially Subscriber for the awesome work done, and making it freely available for the Notos owners!

So I printed me a long snout moderator, and it works super! The only drawback is that the gun is now slightly longer, but there's no free lunch...

I always test all my moderators with a digital sound pressure meter, and measure on a 45 degree angle from the bore/moderator end at a distance of 1 meter (3.3 ft)

This got me the following data: (std unmodded Notos, doing 232mps/761fps with Crossman Hollow Point:)

Without the red OEM factory insert        113.7 dB
With the red OEM insert:               avg.  100.5 dB  (7 shots measured, low 99.9 high 101.3)
With Subcribers Longsnout insert: avg.   96.1 dB  (7 shots measured, low 95.3 high 96.9)
Measured at 10cm from my ear:              90.6 dB

A tremendous reduction in sound pressure! But 90 dB at the ear is potentially still quite damaging... (it doesn't SOUND damaging at all though...) Unfortunately I did not get the "quieter than a fingersnap" result that Firewalker got, in order to get that magnitude of sound pressure reduction I guess we would need to resort to a really large can (big soda bottle size type).

There is this gentleman offering a 3D print called a "deciball" online, and he claims a 15dB reduction in sound. But this thingy is suspicously small, (and unsightly looking) so I think the number is a comparison from using no factory insert at all and his design. Which would make it just about as good as the factory insert. (it could change the pitch so it could be perceived as being quieter). I do not believe the claimed 15 dB reduction is the difference between the factory insert and his. (thay would be miraculous for such a small volume) There are not many user reviews, and the ones that are are not very conclusive, other than that it does work at least some.

So to get the Notos noticeably queter than out of the box, I fully endorse Subscribers moderator, a measured 4 dB reduction from the stock Notos!

Thank you again Subscriber for making your work public!  8)

TennX:
I have one of the mentioned inserts and I agree there is some reduction..I did buy the machined kit that allowed for 1/2x20 moderator….but decided I didnt want to tackle removing the factory set up…most all my guns have some sort of moderator…but its now a mute point as I dont worry about the neighbors anymore…lol…like most I really like this gun…but its long since quit being light ……good luck

smythsg:

--- Quote from: 2A Georgia on May 26, 2024, 04:22:46 PM ---M4 grub screw, barrel/TP area o-rings and plenum kit ordered.
Time to start disassembly....
Questions for those who have gone before me;
Does anyone know the length of the factory exhaust valve stem (considering TR Robb again like my pp800r build)?
Anyone going loud-n-proud with no shroud or moderator after the plenum swap?  I hunt and have started to work 25yards at the LGR so may not need BY friendly...
Here are my options for post plenum moderator no particular order but love to hear opinions experiences
1. Loud-n-proud.  Cover the 1/2UNF threads and rock on dude :-)
2. $35 Buck Rail moderator.  Same size/shape but concerned about the Neanderthal and 3D parts...
3. Pay the gentleman who had free moderators his fair price.  I'm sure the performance is wonderful, same concerns for hunting durability....
4. DonnyFL Tanto $99 smaller diameter 1.25" shorter and machined from solid metal....might survive Neanderthal use.....
5. DonnyFL Tatsu $130 slightly larger diameter and 2" shorter...could be nice for stomping through brush.....

Looking forward to strong opinions/experiences....

--- End quote ---

Charles, as you know I have a Donny FL Tanto on my Escape UL and it has served me well over a couple or three years now. It has held up to all the thick brush hunts I have been doing.  ;D












































































































































2A Georgia:

--- Quote from: smythsg on June 18, 2024, 10:43:50 AM ---
--- Quote from: 2A Georgia on May 26, 2024, 04:22:46 PM ---M4 grub screw, barrel/TP area o-rings and plenum kit ordered.
Time to start disassembly....
Questions for those who have gone before me;
Does anyone know the length of the factory exhaust valve stem (considering TR Robb again like my pp800r build)?
Anyone going loud-n-proud with no shroud or moderator after the plenum swap?  I hunt and have started to work 25yards at the LGR so may not need BY friendly...
Here are my options for post plenum moderator no particular order but love to hear opinions experiences
1. Loud-n-proud.  Cover the 1/2UNF threads and rock on dude :-)
2. $35 Buck Rail moderator.  Same size/shape but concerned about the Neanderthal and 3D parts...
3. Pay the gentleman who had free moderators his fair price.  I'm sure the performance is wonderful, same concerns for hunting durability....
4. DonnyFL Tanto $99 smaller diameter 1.25" shorter and machined from solid metal....might survive Neanderthal use.....
5. DonnyFL Tatsu $130 slightly larger diameter and 2" shorter...could be nice for stomping through brush.....

Looking forward to strong opinions/experiences....

--- End quote ---

Charles, as you know I have a Donny FL Tanto on my Escape UL and it has served me well over a couple or three years now. It has held up to all the thick brush hunts I have been doing.  ;D

--- End quote ---
Pretty much what I theorized.  I've been in thick brush with you and our micro-machetes.  Tanto will get purchased before August.  It's almost gonna be unfair to have Notos accuracy and subsonic suppressed tree rat headache medicine....

2A Georgia:
BTW Steve, next woods walk I'll bring you some 19.4gr NOE Hunters and some Monster 35gr MPmolds 5.55mm slugs.  My Notos actually grouped the 35gr slugs better than the NOEs but of course about an inch lower at 15 yards.  Kinda makes the Notos a psuedo-mortar cannon

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