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Tuning Fliers-at then end of my wits

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Well, I THINK I have figured it out................don't know whether overtightening caused it, but I had watched an Ernest Rowe video before attempting to remove the shroud and pull the liner, and he made a point about avoiding overtightening the nut, so I was careful about that. I think I bent the sleeve, and once bent, any increase in nut tightness would bend it more.

Buckshutr, I couldn't fell any play of the liner in the nut, but that may be because of the O-rings. So I will keep that in mind.

This could also mean that I didn't ruin my pellet liner by CF sleeving, I just bent the barrel sleeve. We'll see.
 
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New sleeve en route from FX. Further testing shows smaller, neater groups than before I straightened the sleeve as best I could, but there are still occasional fliers. They are all toward 10:00 from the POA.

If I insert the liner without O-rings, and without the liner nut in place, hold the assembly vertically and look down from the muzzle end, it wants to come to rest off-center toward about 3:00 or so. Firearm barrels will shoot AWAY from a pressure point, so this makes sense to me. The bend point is about 1/3 the distance from the breech. One O-ring a few inches forward of the breech increases the displacement and still gives fliers. Add another one, or two, past the bend toward the muzzle, and the fliers persist. Increasing liner nut tension makes things worse. So I tried just one O-ring, about 6" back from the muzzle, with light liner nut tension. This AM at 0630 with no wind it is printing tight little 1/2" or smaller 5-shot groups, often with two or three touching, and usually with a "flier" toward 10:00 turning a 1/3" group into a 1/2" group.

I kept one O-ring because it's hard to maintain my liner index without it. I may try no rings at some point. Right now, the wind has returned so I'm done testing. 23 gr H&N .218 slugs, average velocity for 10 shots 925, ES 7, Sd 2.4
 
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After you get your new outer barrel sleeve, may I suggest a carbon fiber sleeve epoxied onto your liner, and just get rid of those liner o rings. The CF sleeve will reinforce your liner, and assist in the accuracy dept. Just make sure you wipe down the liner with acetone first to remove all oils, and follow the Ernest Rowe procedure in epoxying the liner to the sleeve.



https://youtu.be/Lkwt0gVpzdI





the CF liners can be found here-



https://910airguntuningandrepairsllc.com/products/carbon-fiber-liner-sleeves-stx-liner-sleeves


 
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A silver sharpie makes a great marker on these liner sleeves to note down caliber, liner type, barrel length, the gun it goes into, along with the twist rate. Just remember to check your twist rate before installing the CF sleeve, lol.



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98EBCBD0-3EE4-411E-8B2C-ACE0D2996B6B.1617864108.jpeg

 
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Heh. CF sleeve is how I got into this mess in the first place, because I think I bent the barrel sleeve trying to remove the shroud. Before I do that to my Superior liner, after the new barrel sleeve arrives I will try out the pellet liner that I sleeved with CF sleeve from 910 following the video from Ernest. If it shoots well, maybe I will consider sleeving the Superior.

Dirty barrel it most certainly was not, if you go back and read what I did to exclude that as a cause. And I've put 300 slugs through it since I reduced the bend, with zero wild fliers, without any sort of cleaning. Before, I couldn't zero it, and now it groups so that I can recognize the effects of wind or pulling the shot. Those "fliers" are an order of magnitude smaller, like a half inch at 70 yds instead of 1 1/2".

But I did learn a whole lot from the process, so there's that.
 
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It’s good to hear that at 300 slugs your gun is holding. My Impact went off the reservation a couple nights ago and started shooting the kind of groups that you don’t even know which way to move the scope. Pulled 3 patches through the barrel and it’s back to normal. I still haven’t figured out when exactly to clean it. It’s just not showing a pattern to when it gets dirty. But right now it might be around the 300 mark. I never had a dirty barrel throw fliers, it just shoots bad or I guess shoots nothing but fliers. Glad you have it figured out. 
 
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Vetmx, at 400 rounds my groups opened up, I cleaned, and the groups tightened again. I guess polishing doesn't prevent that, nor does lube since the H&N are lubed. They do lose some lube as I sort them though. New barrel sleeve soon, then I'll know for sure.

Corvid, I have certainly seen profound effects from velocity variation. Usually a small movement of the valve adjuster is enough to move my POI. I did a lot of this work in 20-25 degree weather, and can't really say it affected velocity much. If I left the rifle out in the cold for an hour, my first few shots would be slower, then back to normal.
 
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Replacement barrel sleeve arrived yesterday. Installed it and indexed my liner to its usual position. Just now with no wind I found that POI at 70 yds had moved quite a bit, about 5" up and left. Interesting, because that is the diametrically opposite direction of the bend in the old sleeve, which makes sense. Groups are small and no fliers except the ones I make myself. I'm sure the harmonics are changed as well, so there may be room for further improvement.

O'Doyle, I did up a batch of 50 slugs washed and lightly lubed with Lemon Pledge, with no improvement. But that was with the old sleeve. I still have a bunch and will re-try them.
 
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This is eight or nine shots at 70 yards. The 9:00 shot was first, with a little 5:00 wind, maybe 2 mph. I stopped and I fired 3 rounds which went into the left half of the central cluster. Then I dialed one click right. Then a 2-3 mph wind came up from 7:00 as I fired the fifth, hitting at 3:00, which is consistent with the known effects of wind on a slug. Then the wind dropped and the rest went into the right half of the central cluster.

This is the behavior I used to get before I attempted to "improve" my rifle. 23 grain H&N .218 slugs sorted by weight. These were all 23.4 gr. at about 920 fps.



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I have been reading this thread from A-Z and I have to say that this one of the best threads I have read. For all ( especially FX) shooters this should be a “ MUST READ” as Khornet gave a fine listing of know how and skills to learn from . Also many good comments of course from other forum members. ! When I had a similar problem as Khornet I was lucky enough to order a new liner straight away and found the reason of my fliers there. I also damaged the liner myself by a stupid action but was not 100% sure about that. Decided to pay the “stupidness penalty” of around 100 USD and was o.k again. The good thing from such “ events” is that you do your research an go through all those mentioned potential causes as described so fantastically in this thread. This way you learn about your gun and this is a good thing when you inderstand why and how things work like they do. Indeed do not tighten the liner nut and barrel grubnut too tight. Very slightly over handtight is fine. Tiny bit of bluer loctite on grubnut will do good job but don’t tighten it too much ! Carbon sleeve vs o-rings on liner is still a very debatable issue for me . The fact that you “fuse” 2 materials together with different properties is holding me back from using the CF sleeve as harmonics might be changed in different temperatures and that is undesirable to me. Harmonics play a very important roll in airgunning and I believe FX have to do a little more tuning on their o-ring construction. The position of the orings should be fixed and not going all oever the place by taking out and reinstalling the liner. I know a little “ridge” of tape can keep them in place but I suggest a factory solution should do,the job. Re cleaning I found that FX liners do need far less often cleaning than other barrels I used ( LW) in the past. Because of the way of producing the FX liners the inside is super smooth hence not picking up dirt particles easy. Anyhow. Lesson learned here is not to force/ wiggle your shroud loose like The Hulk when it is a bit tight but operate with care avoiding any bending here ! With Fx I believe ( compared to mentioned Kalibrgun, Edgun, Taipan, Vulcan ) you should be a little bit more careful about this kind of of issues but in the end the way of constructing FX is giving us relativ light weight and very easy adjustable toys that are made well in general with leading technology bringing our hobby to the next level. Postings like Khornet’s are the proof that this hobby can give a lot of satisfaction and frustration but with this forum in the background and a bit of know how the path to satisfaction can always be found!! Thanks Khornet ( and others) for your fine contribution ! 
 
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I have had accuracy problems with my FX Crown. After 100 plus shots the accuracy would become erratic. Cleaning the barrel would not always solve the problem. After getting a bore scope I figured out what my problem was. At the end of the barrel where the chock is there would be lead smeared on the rifling. I could not see the lead with out the bore scope the barrel just looked clean to my eyes. Once I found the problem area I could go after it with a brush and solvent. I would reinspect and go at it again if all of the lead was not removed. Guess the FX liners were not so perfect after all. After figuring out what the problem was my accuracy is fantastic.
 
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