GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: skorec on June 01, 2017, 05:24:10 AM
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My .22 NXWerks QR bullpup is probably the same as JKHAN Noblesse but unchocked 450 mm LW 1:14” barrel is used.
Because Monsters and Beast still started spiraling at longer distances a I have modify it to use JSB Heavy by Huma reg. ( 160 bar ) and hammer spring power reducing.
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After dissasembling I have found out that barrel is 450x14mm chocked , 1:21”
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But I am still not satisfied with long distance accuracy and therefore I am thinking to change the barrel to choked 605mm 1:17,7” LW barrel. I also plan to increase thick of “muzzle cove o-ring” to enable resonance similar as floating barrel.
What are your opinions about this project ?
Do I use 16mm thick barrel ?
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I have changed the original ( 450x14mm chocked , 1:21” ) XY barrel to ( 605x16mm chocked , 1:17,7”) LW barrel and velocity has increased from 277m/s to 292m/s and accuracy has increased nearly two times.
Barrel is floating on rubber O-rings and scope rail is not fixed whit the air tube !!!
https://www.gatewaytoairguns.org/GTA/index.php?topic=128618.msg1263775#msg1263775 (https://www.gatewaytoairguns.org/GTA/index.php?topic=128618.msg1263775#msg1263775)
I am satisfied however trigger is not too good.
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These guns seem to be Evanix copies so you should be able to reshape and polish the sear for better trigger feel.
http://i920.photobucket.com/albums/ad47/abbababbaccc/sear-2_zps43122e58.jpg (http://i920.photobucket.com/albums/ad47/abbababbaccc/sear-2_zps43122e58.jpg)
http://i920.photobucket.com/albums/ad47/abbababbaccc/sear-3_zps96593d95.jpg (http://i920.photobucket.com/albums/ad47/abbababbaccc/sear-3_zps96593d95.jpg)
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Thanks, Interesting and also audacious reshaping. Probably I will do it.
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Via the air pressure regulator ( 160bar) the speed of pellets is constant but still there is some vertical inaccuracy seems depending of air pressure at tube ( 230bar-170bar ).
Maybe I have to change O-rings to the ticker one to let the barrel to float more free or better tell more independently of air tube dimension.
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At first step I remove front barrel fixing.
The POI has moved at 15cm for 72 distance but verticular inaccuracy reduce to the 3cm.
At next step I has equipped front barrel fixing via ticker O-ring.
The POI moved to 8cm but verticular inaccuracy reduce to the 2,6cm.
I have found out that barrel fixing is very important issue.
Is there anywhere described whith the principled pictures too the ideal barrel and scope rail fixing on PCP gun ?
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If they are no any barrel fixing recommendations I stay on myself opinion:
The barrel have to be fixing at its own position without touching on it from any side.
Power of fixing or O-ring thickness have to be enough soft to avoid to transfer deformation from air tube . I believe that just know am able to group inside 22mm at distance 72m. As you may see on the picture the wind did horizontal inaccuracy.
Unfortunately I do not know how much ( 0,5mm ? ) air tube is deforming by pressure changing 230-170 bar.
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It does not have to more much to cause the issues your having. Why not open up where the barrel rests in the barrel band?
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I you mean does not use front and middle barrel bands/fixings at all I am not sure if the resting barrel band at JKhan is strong enough also for eventual gun falling .
The question also is if is it possible to reach better grouping then 22mm at distance 72m in windy whether.
But I will test it probably but I need to tune trigger first and test also another calibers ( 5,50mm, 5,51mm, 5,53 ) of JSB Jumbo Heavy
I do not know which caliber chocked LW barrels mainly like.
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Have I recrown blank LW barrel or is it better do not touch it ?
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No any suggestions ?
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If I am sure that the shoot had been done OK ( not drag ) then the hole of pellet is obviously at the 2cm middle of target see the picture. Approximately one of them only fly out without dragging . Therefore I am afraid to touch barrel crown .
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Have I recrown blank LW barrel or is it better do not touch it ?
Pleace advice me.
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160 bar is "VERY" high. What is your velocity?
Knife
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As you may see on pictures velocity for JSB Heavy 18,1gr was 290m/s=950FPS
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Grouping increase significantly after I have done fully floating barrel.
Still I had 6-8 fliers from 28 Jumbo Heavy pellets.
Too heavy 605mm x 16mm LW barrel is falling 0,4mm at front.
What about to shape barrel to conus/cone ?
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Still I had 6-8 fliers from 28 Jumbo Heavy pellets.
At what speed? You should try it at about 880-900 fps max.
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YES I have 950 FPS. I will try to decrease it.
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After 5 hours finding out that the best velocity for JSB Jumbo pellets I have the next result :
Jumbo 16gr ……….......1010 FPS
Jumbo heavy 18gr … 970 FPS
At lover speeds ( 800-900 FPS ) the accuracy was 1,5-2x poorer .
Maybe very long and tick barrel prefer higher velocity ???
Importent notice.
Too much flyers shoots had been occurred surely only by very hard trigger.
It seams that I realy need better triger sear !!!
Why the heavier pellets shot above ?
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Today was calm and the barrel also probably have set more. 8)
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My only thought is that you're getting more comfortable with the trigger and the barrel is getting more broken in. This is the 16mm barrel, right? From everything I've read, JSB seem to prefer right around 880 or so FPS, and yet here you are will solid proof yours shoots better at higher velocities. The only thing I can think of is to keep shooting and continue breaking the gun in as an assembly of parts. IE: don't change a thing- just keep on shooting :)
Side note: very interesting (in a good way) seeing how free-floating positively affected accuracy for you.
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Thanks, Yes I need to insure about long time stability.
What are yours best groupings at 70+ yd from .177 and .22 calibers.
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Today I have improved looking a little bit with using thermal foam tube but I am not sure If I not decease the accuracy. 1/3 pellets are out of MOA :o
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Sorry I have to add my best grouping also here to let you see which gun it done.
Please let me know which is the easiest way (neck on valve stem ? ) to reach 985 FPS with 25gr Monster pellets too ?
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I wanted just insure myself if the Jumbo Heavy accuracy is still acceptable at 295m/s.
Notice,
Very sorry for my horrible mistake when I used word gays not guys what I was meaning.
Sorry again.
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It looks like that my "free floating barrel" is not long time stable. The pellets was sometimes shooting wrong mainly lower after some shooting session.
Therefore I start another project “free floating barrel shroud” .
I centered shroud to the barrel patiently and fixed it at the muzzle by using plastic tube equipped with rubber O-rig. A matter of course front shroud band I have centered and enlarge too.
Just now is shooting acceptable ( 7 pellets of 10 inside 15mm at 71m - sorry I can not add the picture - Explorrer supress me it add ) but only time tell me more about of stability.
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Sorry I have to praise my gun again .
23 of 30 pellets are inside 1*MOA.
I afraid a little bit to touch the gun for swapping to the SS valve. :-\