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Fps all over the place on BRK atomic regulated gun

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BeMeUp said:
Bought a used Atomic was never really accurate, could put hole in hole but not too often, put on a fx chrono and my fps is all over the place ,don’t feel nothing blowing back from probe ,tried waiting different times between shots that made no difference does this sound like a barrel seal?
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@BeMeUp I’ve blown a few breech orings, but never chronographed the shots. I would think that if it’s a blown breech o-ring you might have consistent reduced velocity. If you think that the breech o-ring is the culprit, it is relatively simple to replace if they have the same design as older Brococks. This is just a guess, but it sounds to me like your regulator may have an issue. Have you pulled the regulator? What do you mean by “my fps is all over the place?” Can you provide us with a shot string screenshot?

What do you think @nervoustrig? @L.Leon?
 
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@Ezana4CE, the OP mentioned that his Atomic “was never really accurate”. We know from thousands of pellets down range that it is very accurate. I second, that from the description? It seems to be a regulator issue. The OP should consider reaching out to the seller. To find out if he “adjusted the regulator and or the HS”. OPs problem definitely isn’t the norm for the BRKs.
 
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L.Leon said:
@Ezana4CE, the OP mentioned that his Atomic “was never really accurate”. We know from thousands of pellets down range that it is very accurate. I second, that from the description? It seems to be a regulator issue. The OP should consider reaching out to the seller. To find out if he “adjusted the regulator and or the HS”. OPs problem definitely isn’t the norm for the BRKs.
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No way BRK made just one defective gun? Just kidding L.Leon. Couldn’t resist.
I would change the breech seal, see what happens and if no resolution try tuning the gun from scratch.
God only knows what some people who don’t know how to tune subject a perfectly good gun to.
If that doesn’t fix it then start looking for a problem.
 
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Chukar60 said:
No way BRK made just one defective gun? Just kidding L.Leon. Couldn’t resist.
I would change the breech seal, see what happens and if no resolution try tuning the gun from scratch.
God only knows what some people who don’t know how to tune subject a perfectly good gun to.
If that doesn’t fix it then start looking for a problem.
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Good stuff @Chukar60, no offense taken…🙏
 
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I had the same on my outing on Saturday, i had a really hard time getting a just sort of flat shot string on my Maverick.
Okay before that the rifle was leaking at the bottle and i fixed that alright.

Today i changed a couple of O-rings in the low pressure REG too, and found out that the HUMA complete repair kit i have, well its only for repairing one of the REGS as far as i can see by the amount of the very smallest O-rings in a FX regulator.

Got a lot to do in the next 2-3 days, so no time to run the rifle with the chrono, but i should be able to get that done before the weekend that might see shooting weather.
It was really strange, i have spent MANY hours on the maverick and i think i know how to find a sweet spot, but not last Saturday, and it made no sense the readings i got.
 
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Ezana4CE said:
@BeMeUp I’ve blown a few breech orings, but never chronographed the shots. I would think that if it’s a blown breech o-ring you might have consistent reduced velocity. If you think that the breech o-ring is the culprit, it is relatively simple to replace if they have the same design as older Brococks. This is just a guess, but it sounds to me like your regulator may have an issue. Have you pulled the regulator? What do you mean by “my fps is all over the place?” Can you provide us with a shot string screenshot?

What do you think @nervoustrig? @L.Leon?
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571 to 639 fps with new o ring even got some higher discrepancies on some other shot strings it will move poi at 35 yards 2 plus inches. Can get 3-4 cloverleaf shots then a couple a whole mil or more off using HN match 10.65 if I shoot 8s their lucky to get a sub moa at 25 yards I guess it’s time to tear apart I got it used from AoA so no way to contact owner to see if he did anything
 
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BeMeUp said:
571 to 639 fps with new o ring even got some higher discrepancies on some other shot strings it will move poi at 35 yards 2 plus inches. Can get 3-4 cloverleaf shots then a couple a whole mil or more off using HN match 10.65 if I shoot 8s their lucky to get a sub moa at 25 yards I guess it’s time to tear apart I got it used from AoA so no way to contact owner to see if he did anything
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Why not reach out to AOA?
 
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If the regulator is not working you should get a bell shaped curve like it didn't have a regulator. Lower velocity at higher tank pressure, higher velocity as the pressure drops. My Caiman with a Huma regulator jumped around some at first, I found gobs of silicone grease on the springs. Cleaned most of that off and it works much better. Goofy thing was it quit working at all a little later. O-ring on the regulator adjuster was completely free of silicone grease. I can't see how it made sense to slather it where it wasn't needed and put none on an O-ring that needed a little. But all fixed now.
 
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BeMeUp said:
571 to 639 fps with new o ring even got some higher discrepancies on some other shot strings it will move poi at 35 yards 2 plus inches. Can get 3-4 cloverleaf shots then a couple a whole mil or more off using HN match 10.65 if I shoot 8s their lucky to get a sub moa at 25 yards I guess it’s time to tear apart I got it used from AoA so no way to contact owner to see if he did anything
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@BeMeUp Aside from the H&N pellets, which other brands and weights have you tried? What’s your regulator set at? Does the regulator’s set pressure change at all during your shot string(s)? Out of curiosity, what is the power knob setting? That’s pretty low velocity you’re getting. I assume yours is a .177 caliber Atomic.
 
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Chukar60 said:
No way BRK made just one defective gun? Just kidding L.Leon. Couldn’t resist.
I would change the breech seal, see what happens and if no resolution try tuning the gun from scratch.
God only knows what some people who don’t know how to tune subject a perfectly good gun to.
If that doesn’t fix it then start looking for a problem.
Click to expand...
I feel like I’m being talked about…lol definitely been guilty of adjusting things before I knew what they do.
 
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Ezana4CE said:
@BeMeUp Aside from the H&N pellets, which other brands and weights have you tried? What’s your regulator set at? Does the regulator’s set pressure change at all during your shot string(s)? Out of curiosity, what is the power knob setting? That’s pretty low velocity you’re getting. I assume yours is a .177 caliber
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JSB 8s10s AA 8s 10s FX 8 s 10s RWS and MiesterKrugeen 7s my gun won’t get 700 fps on high power with hammer cranked all the way in. Finally found a video on 177 with chrono numbers should be hitting 800+ fps with 8 gr. I’m getting on high what she was getting on low this is both guns in carbine setup. When she had on high power in pistol set up and cranked in all the way to 6 which is where mine stops to she hit 826 fps with 8 gr. I’ve had 1 outta 10 jump 100 fps but it’s not consistent.Lots of videos on the 22 most on the 177 were from the English setup plus while looking I found 2 videos of how to disassemble and reassemble their XR line of guns very well made videos , so I think I definitely have a regulator issue since I’m not coming close to the chrono numbers and getting no air leaks I don’t mind popping the tube and checking the reg. These guns when it comes to tearing down they are pretty easy there’s not a lot of parts and those videos show everything you don’t even need to be mechanically inclined to tear apart and reassemble .I have a Concept xr and know how good these guns shoot I love taking the empty Friday nite pizza box out to my 30 yard mark and opening it up to expose grease and remnants within minutes the bugs are landing and I’m splatting them I wanted this gun for field target but not till I find outwhat’s up
 
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BenjaminM said:
I feel like I’m being talked about…lol definitely been guilty of adjusting things before I knew what they do.
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I try not to with the air guns to easy to blow a seal like when you lower your reg pressure with out degassing, not that I’ve done that but would have if I didn’t see it on a video on fx impact. I do read the manuals just in case
 
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jarmstrong said:
USED,,, when ever I see a wide es, I suspect a gummy/sticky hammer,,,
dry lube, dry lube only ,,, clean out the hammer chamber also
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What do you use? Ever use Drislide motorcycle cable lube it’s graphite. I’ve only put a couple drops of peligun oil on probe but will try cleaning like you said it’s got to come apart anyway.
 
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