Notos Notos Gen 2 owners — does yours hold zero day-to-day? Mine moves whole groups with nothing changed

[LineofD]

Looking specifically for Notos Gen 2 owner experience before I send mine back to Umarex.

Problem: the rifle can shoot very tight groups, but the entire POI moves.

• ~80% of the time, zero is noticeably different the next shooting session.
• I've now had it happen twice during the same session.
• The same-session shifts happened with:

• no refill
• pressure still above regulator
• no turret adjustment
• same FX 15.9-gr domed pellets
• same exact 30-yard distance
• same Matrix benchrest
• same target sheet — I simply moved to the next bull

• Some shifts are large enough that correcting them would require roughly 10–20 scope clicks.
• These are whole groups moving, not individual flyers.

Things already ruled out:

• Scope rings tight
• Ring-to-Picatinny clamps tight
• Parallax/AO set for 30 yd and verified by moving my eye — reticle stays stationary on target
• Same ammo ~600 pellets spent trying to diagnose this
• Same supported shooting setup

Equipment:

• Umarex Notos Gen 2
• Monstrum Panzer 2–10×40 AO
• FX 15.9-gr domed pellets
• 30 yards

I can also feel a very slight amount of movement between the upper/barrel assembly and air tube, although the accessible top rail screw is snug.

Mine was one of the early Gen 2 rifles delivered in July.

What I really want to know from other G2 owners:

1. If you zero yours, put it away, and pick it up tomorrow, is the zero normally still there?
2. Has anyone had whole groups abruptly move like this?
3. If yes, what was ultimately wrong — barrel/receiver/rail retention, scope, regulator, or something else?

At this point, if other G2 owners routinely get a stable day-to-day zero, I'm going to stop troubleshooting and let Umarex handle it under warranty. Ex-military and have been shooting for 30+ yrs but this is my first PCP so I don't have a good basis for comparison. Thanks for any experience sharing.

Photos:
1. Moving groups example -- no turret change
2. Example of groups I can sometimes get when the damn POI isn't skittering around

 

[pan60]

Welcome to HAM!

 

[Pumacarl]

I don't need to have owned one to tell you that is not normal for ANY airgun. Something is definitely wrong. Good luck, and welcome to HAM!

 

[FL22]

Hello and welcome to HAM, good luck with getting it sorted out.

 

[Zelos1]

do you have a way to check that’s your scope is level each time?
When i shot bullseye pistol, group position was always something “mechanical” with the grip or arm position or something insanely simple like that.

 

[JimT66]

Not outta mine. I've fired a couple hundred of the same FX domed 15.9's and the Hades, and its stayed rock solid since zeroed my scope. Something definitely ain't right with yours. Got mine towards middle of August.

 

[PapaT]

If you have another scope, I would try that as well. I have had huge changes in poi just because scope would change with temperature/sunshine warming. If it's a known good scope, then something is definitely not right with the rifle.

 

[LineofD]

Hi all, appreciated all the input on my problem and wanted to update.

Sorry it’s been a while — I was overseas for a few weeks and just got my gear.

I heard the comments about the scope, so I decided to remove that variable as much as I reasonably could. I ordered both an Athlon Talos 4–16×40 and a Hawke Vantage to compare against the Monstrum. The Athlon is mounted now.

A few useful data points from today:

• Before touching the turrets, I shot a tight 6 shot group. It’s not centered, but it’s tight enough that I think it shows both the gun and I are capable of grouping.



• After zeroing, I shot the other bullseye below


• No turret changes between those groups.
• No refill, all on the regulator
• Same FX 15.9-gr domed pellets.
• Same bench/rest at same 35 yd distance.

What I’m still seeing is basically the same behavior: some shots are near the expected POI, then several shots shift significantly high/right. I literally saw the rounds strike up and to the right as I fired.

This is now happening with the Athlon, not the original Monstrum scope, so I’m becoming less convinced the optic itself is the root cause.

The common pieces are now:

• Notos Gen 2 itself
• Same Monstrum adjustable-height rings
• Same rail / receiver / barrel assembly

I have a set of fixed-height Picatinny rings coming that use a more positive cross-slot engagement rather than the adjustable-height design. That should let me rule the existing rings in or out pretty cleanly.

Will update after I swap out the rings when they arrive. Btw, the 16x on the Athlon is super clear but I have to get a sunshade...also, the covers are so cheap looking it would have been better for them just to have left them out, wonder why they did that.

 

[LineofD]

Solved the problem (fingers crossed)

Today I got new fixed height integrated block ring mounts for my picatinny rail. As I put it on, I checked on 5 screws along the rail.



Using an FAT screwdriver, I checked all of them at 8 in-lbs to start and 4 of 5 turned. The two deeply indented ones on both sides of my pinkie fingertip in particular were loose and I believe secure the barrel assembly. I couldn't find any specifications for torque so torqued them down to 12 in-lbs.

I finished mounting the rings and gave it a try. Once I dialed in, the drifting shot groups and wildly differing POIs disappeared. With the 16x magnification on the Athlon, I was hitting pretty much everything within a dime.



Huge relief after changing out almost everything one by one. I won't know whether it was swapping out the adjustable height mount with the fixed one or tightening the screws on my Notos, but after now shooting about 6 magazines and seeing consistent groups, I'm cautiously calling it case solved.

Thanks to everyone who gave good advice and I hope this helps someone running into the same problem. If you send the gun to Umarex, I'm guessing they'd just tighten the screws