Help with pellet spiral

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C

carpp

Member
Jun 28, 2016
22
1
UK
Ive got a spiralling pellet issue with my .25 fx 500 at 50 yards it groups nicely but beyond that pellets start to spiral wildly, ive tried a few different types of pellets, cleaned the barrel, checked the crown for burs using a qtip, checked the transfer port the same way and couldnt find anything, ive pushed pellets through the barrel and none of them seem to be marked in anyway that would suggest that the barrel is the culprit, fired with the moderator on and off and single loaded them into the breech to bypass the magazine and they still spiral. Does anyone have any ideas? my muzzle velocity is around 780 with jsb heavy 33 grain.

cheers
 
Carpp, how does it shoot 25.4 Kings? I tried some 33.94 MKII's and I think the lube on them was not a good combination with my 500. They shot better once I got all the lube off. I'd pull a couple of dry patches and try some 25.4's again. It might be that 780 isn't fast enough to stabilize the heavier pellet. I'm shooting the heavies at 875-880 and they are shooting well, this is just the MKI's though. You might also double check the cone on the air stripper and make sure there's not contact there with the pellets.
Jimmy
 
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You didn't mention which power wheel setting you shoot with so I assume you are shooting on it's highest power setting. If indeed this is the case, your rifle should be shooting a 25 grain pellet around 865-875 fps. I'd venture the heavier 33 gr would be in the 800-815 fps ballpark. The 500 has an extremely long barrel which makes the velocities you are getting seem suspiciously slow so that may be worth looking into after you figure out what is causing the pellet spiral.

Anyway, here are some suggestions for vetting out pellet spiral:
  1. Try filling to just 200 bar to see if it removes the spiral
  2. Try each of the three power setting to see which results in the least pellet spiral
  3. Replace the breach o-ring with a new one
  4. Try shooting some pellets into a barrel of water or clay so you can inspect the pellets for deformities
  5. Look through the barrel using a light at one end to see if you notice any damage inside the barrel
  6. Check that the barrel is firmly attached and seated in the breach
  7. Try using some pellet lube
  8. Use a bubble level or anti-cant device when shooting
  9. If you have a barrel band, try removing it.
  10. Check that the bottle isn't pushing against the underside of the barrel
    [/LIST=1]
    That's about all I can think of off the top of my head. If after performing all of the above steps, send the gun back for service.
 
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Thanks for the replies, im pretty sure the rifle has done it all along, there is no difference with or without the mag the same applies to the air stripper, ive tried jsb 25 grain, h&n barracuda, jsb heavy, fx smooth twist and h&n grizzly all have the same spiral effect some worse than others, at the moment i shoot at high power but have adjusted the wheel to test at both medium and low and the results are still the same, im reluctant to send the gun back as when i phoned up to discuss it with them they said if it accurate at 50yards then they will send it straight back to me.

here are some pictures of the barrel crown and some pellets i pushed through the barrel last night.





 
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Tricky one!

I can't see much wrong with those 'fired' pellets and the barrel crown looks OK ...

But as said earlier 780FPS is rather too slow for 33grain pellets.

Incidently, do you shoot with both eyes open ? (because there is a Perception Problem with that - basically one eye is looking down the scope tube whilst the other possibly can perceive / see :) the pellet leaving the muzzle and rising etc, it's also not looking down the straight line of the bore ((left eye, in my case)). Just a possible that.

I think you'd need to Walk down the Target to get a full grip on what's happening - ie: shoot at say 60, 70, 80 yard targets in one session to see if there's an obvious pattern.
 
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Interesting !
I can definitely see 'yawing' of the pellet for a section of it's flight and a "suspicion" of the pellet entering the picture at @ 5:30, using the clockface analogy. (slightly to the right of the vertical ret.stradia or line). If that is occuring then the scope is not mounted perpendicular to the rifle (ignoring the vid camera effect) which would be a sort of built-in Cant error.

In an ideal world the pellet would traverse entirely up along the 6 o'clock ret line, carry on over the centre then drop to the centre, at the set distance.
 
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"Dairyboy"I'm not too big of a fan of how those pellets look. They have good engagement but almost too good it looks like they get bent into a Pentagon shape and it looks like the barrel crown isn't perfectly round either...
Click to expand...
The FX barrels are pentagon shaped because of the twist that is put on them towards the end of the barrel by the FX factory. Instead of grooves the pentagon shape forces the pellets to spin during the last few inches of the barrel.


http://[URL=http://s1124.photobucket.com/user/tomsz2007/media/IMG_558n6_zpszqu2ktq3.jpg.html][/url]
 
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after viewing your vid and if nothing is wrong with your barrel end -> polish it using JB bore products.

There are several posts here on the forum which details the process.I did it and it helps to remove pellet spiraling which occurred after 100-120 shot in mine (MK2 heavy are covered by a sticky product). Now I have to clean it each 400 rounds.
My Gladiator is so accurate with those pellets that I have not yet try to clean them.

Here a picture of a pushed pellet once spiraling pellets appear:




 
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fe7565
"Dairyboy"I'm not too big of a fan of how those pellets look. They have good engagement but almost too good it looks like they get bent into a Pentagon shape and it looks like the barrel crown isn't perfectly round either...
Click to expand...
The FX barrels are pentagon shaped because of the twist that is put on them towards the end of the barrel by the FX factory. Instead of grooves the pentagon shape forces the pellets to spin during the last few inches of the barrel.


http://[URL=http://s1124.photobucket.com/user/tomsz2007/media/IMG_558n6_zpszqu2ktq3.jpg.html][/url]
Click to expand...

Lol learn something new everyday well good to know about that had no idea
 
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Carpp. A lot of effort from your side, and no final solution. At the least the spiraling is somewhat consistent, except shot nr 4 at 2:20. If not clipping this have to be related to pellet "deforming" in a asymmetric shape. I can not see that increasing the velocity will be the fix here, but I may be wrong of course. So maybe dreuf gave the key solution here?
 
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