Brocock/BRK Atomic XR I need some help from the BRK crew

[Chukar60]

I recently purchased a used Atomic XR. Wanting a pistol carbine sized gun and the Atomic looked the best option.
Do not take the rest of this post as any condemnation of the gun. It is very well built and all accounts I have read point to a quality, reliable lower powered gun.
I have been struggling with it. Accuracy has not been good. Accounts of 1 hole groups at 30 yards do not describe what I have been getting. This week I removed the jinky picatinny adapters that a previous owner had installed. Got some dove tail scope rings and bought a US Optics TS 12X scope for it. Accuracy improved but when I was sighting it the gun started to sound off. Not the crisp sound of a tuned PCP, but a sloppy puff sound. Velocities remained fairly consistent and accuracy was not too bad but not really good. The tissue over the magazine area showed no blow by.
I brought the gun to the ranch for the holiday weekend intending to play with it some more. Two magazines in and the sound of the gun got sloppier and then it started hitting about 8-9” low at 30 yards. I could clearly see the pellets in flight through the scope.
I am not at all familiar with BRK products and thought I would bounce this off the BRK fans and see if they can point me in the right direction. I am leaning toward a regulator issue or maybe the power changer has gone south.
Can the reg be easily replaced if that is the issue?
Really like the little gun and am confident once this issue is sorted it will serve very well.

Thanks in advance

 

[L.Leon]

Was going to suggest the O ring in the barrel, but your tissue test seems to eliminate that. When you write velocities remain fairly consistent, are these chronographed velocities? From what you are describing, partifcularly hitting 8-9” low at 30 yards? I would venture to say it’s the regulator, have you checked to see if the TP knob stays firmly in its setting? Its a long shot, but something else to look at. Each of the TP setting has a positive stop. Sorry to read that you are having some issues with your. But am sure you will get it sorted out. AOA is a resource you may consider to query on your issues. They may offer you better insights. Both of mine have been solid, looking forward to reading about your outcome and what the issue was. Good luck…

 

[AirNGasman]

Despite audible clues you mention, consistency over the chronograph would rule out velocity related issues like bad/blown breech seal, valve problems, and/or the power adjusting wheel.

The .22 Sniper XR I bought brand-new wasn't accurate. A bore-camera revealed cavities in several places in the rifling. Warranty barrel replacement solved the problem. Hundred-yard target after rebarrel-

I've since converted the rifle into a pistol/carbine convertible. No accuracy was lost in the conversion-

Sorry I can't shed more light on your problem, but the mixed signals you report are baffling.

"Accuracy has not been good. Accuracy improved but when I was sighting it the gun started to sound off. Not the crisp sound of a tuned PCP, but a sloppy puff sound. Velocities remained fairly consistent and accuracy was not too bad but not really good."

I suspect Airguns Of Arizona could solve the problem. But being you're not the original owner, not under warranty. FWIW, I understand they now also offer a power-upgrade tune.

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[Chukar60]

Was going to suggest the O ring in the barrel, but your tissue test seems to eliminate that. When you write velocities remain fairly consistent, are these chronographed velocities? From what you are describing, partifcularly hitting 8-9” low at 30 yards? I would venture to say it’s the regulator, have you checked to see if the TP knob stays firmly in its setting? Its a long shot, but something else to look at. Each of the TP setting has a positive stop. Sorry to read that you are having some issues with your. But am sure you will get it sorted out. AOA is a resource you may consider to query on your issues. They may offer you better insights. Both of mine have been solid, looking forward to reading about your outcome and what the issue was. Good luck…

The observed velocities were with a chronograph. That was Wednesday while I was setting up the scope and trying some different pellets and hammer adjustment. During this time the tech at the shop mentioned the sound. The more noticeable sound was yesterday and that is when the pellets lost speed. I did not have a chrono but I could watch the pellets drop very fast and I have not been able to visually track the pellets at 30 yards before.
Sorry I should have been clearer on that

 

[L.Leon]

You mentioned HS adjustment/adjustments, that may have something to do with the sound you describe the gun makes. Maybe too much HS for the regulator setting. What were your observed chrono velocities and pellets used? Numbers please, as this will help narrow down your issues. Both of my Atomics have had zero adjustments by me. Simply unbox and shoot, they typically come tune optimally out the box. I send 14.3 CPHPs out of my two…

 

[Chukar60]

You mentioned HS adjustment/adjustments, that may have something to do with the sound you describe the gun makes. Maybe too much HS for the regulator setting. What were your observed chrono velocities and pellets used? Numbers please, as this will help narrow down your issues. Both of my Atomics have had zero adjustments by me. Simply unbox and shoot, they typically come tune optimally out the box. I send 14.3 CPHPs out of my two…

I bought this one used. Hard to say what may have happened before I got it. Mine came with the an external hammer adjuster that is made by a subsidiary of AOA. The gun was not shooting well when I got it. I should say it was not like shotgun patters but it should do better than 3/4” @ 20 yards.
Pellets I was shooting were 14 CPHP’s. They will shoot at about 725 fps max and grouped better at 715 fps.
Then I tried JSB 15.89 these were shooting at 670-680 fps max and backing off the hammer did not improve groups.
What concerns me is the sound the gun makes it is sloppy and no matter how far I back the hammer off it does not change. I was shooting the gun at 30 yards yesterday and about halfway through a mag the pellets started hitting the dirt in front of the target stand.