POI shift on Cricket Carbine 22
*Note – this post is about the Carbine (rifle) NOT the bullpup. I know this is the bullpup forum, but I thought I would find more Kalibrgun experts here rather than anywhere else on the forum.
So this is driving me crazy. I have had two Cricket Carbines and both had this issue. I was advised to cut the barrel band off so the air tube would not affect POI. Seemed to make sense and I thought it solved the problem. It is still moving around. My groups start off left, then shift to center, then move to the right and up. I tested by starting with a fresh fill. I shot 5 shot groups on individual targets and you can see the progression in the pictures. I did not include every target, but they show a steady progression. Almost every group can be covered with a dime which at 40 yards is good for me, but the POI is moving so much that I can’t use this for hunting or target shooting. The regulator seems great with an average velocity of 895 with an ES of 5 shooting JSB 18.1’s.
Then I shoot a couple of cards that are on target. Then it begins to shift to the right and up.
I am at a loss. This gun shoots small groups when I do my part, but I can’t seem to fix this. I have tried several different scopes and the problem persists. I really thought grinding the barrel band off like Ernest Rowe suggested would fix this.
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Those are the points I’m going to check next. I think you and SECoda have it and others on the yellow suggested the same.
For example I had to rework my forend of cricket stock. I figured out some tension between air tube and wood after stock bolt tightened. Also behind corners I sanded with Dremel slightly. There must not be a tension. Bolt screw tighten with care. 😉
No – the classic POI shift you are describing is not “pilot error”. I wouldn’t waste time on that. Most likely still the stock or some pressure on the barrel but it could be a number of issues with the airgun. As I mentioned certain AA PCPs all do it – it is in their design or assemblage. Mine took a little stock rework to fix it.
If the barrel is truly clear then checking the stock fit and attachment pressure would be next for me. I have fixed two different guns with this issue. One was pressure on the barrel and the other had a stock fit issue. The stock made contact on one point but you could keep tightening it as it warped a bit. The pressure may be on the air tube. I know someone on here a few years ago claimed the same POI shift was a changing barrel harmonic. I don’t know about that one. Earnest probably would since he has fixed so many of these. As I said it is real common. I have owned 17 PCPs and probably five on them had a POI shift for one reason or another.
It might cost you a few $ to fix if you have to ship it. Everyone should own a spare or two. 😉
I’m always open to the possibility that it is my fault, but I have three other pcp’s, including an Air Arms s500 and a Vulcan bop that I have no trouble with shifting poi. Not to mention that the pattern on this gun happens every fill the same way. I think it would be harder to make the patterns move that way deliberately every time by changing my cheek weld than it would be to have the poi stay the same. Especially since it is grouping and not scattering the pellets. That would be a neat trick! In this particular instance, it’s the gun not me I’m pretty sure.
To shooter: the reason I have had two is that the vendor was nice enough to send me a second gun when the first exhibited this behavior, I thought the second was better. I couldn’t return for a refund at that point. No, I didn’t go out and buy another one.
Also it was asked: Yes, the barrel is completely free floated. There is nothing touching the barrel or ldc once it leaves the receiver.
It’s almost a common assumption that for airguns that utilize a barrel band/clamp, POI shift would be likely as a result of the air tube compressing and contracting as pressure drops or rises. I used to arrive at the conclusion that this was the culprit when I was frustrated with my Air Arms S410 Xtra’s POI changes (a long time ago). I mean it’s only logical to believe that the expansion and contraction of the air tube would most definitely affect the direction of the barrel given that the band binds them together; thus, if the air tube moves, the barrel moves along with it. (It’s even easier to make this claim with an S410 Xtra because it has a VERY LONG air tube.) I even ordered a custom-made barrel band that used grub screws instead of an O-ring (which the OEM one uses) thinking that the rigidity would prevent any micro-movement of the the barrel/shroud. It didn’t. Not long after, and after much pondering, I thought that I wasn’t being fair in blaming the gun, so I set out to verify if indeed the barrel band was the reason for the issue by seeing it with my own eyes.
What I did was mount a green laser to the shroud of my S410 and adjusted the dot so that it was directly behind the crosshairs of my scope at my zero distance. I did everything intentional to try to get the dot to move from its original position by tapping the barrel with a great amount of force, pushing it left, right, up and down. I also tested tested to see if there would be any deviation of the dot across all pressure levels (from 210 BAR to 10 BAR), and let me tell you, the dot stayed exactly where it was set at. Obviously, the dot would move when I did what I stated to the shroud while viewing through my scope, but it always returned to its exact location when I let go of it. This discovery is one of several reasons that prompted me to focus on refining my shooting technique. And to add to my statement above, in which I said that it was unfair for me to blame my rifle, it is also the fact that I simply did not have the state-of-the-art tools and technology to determine the reason for this issue as perhaps, well, Air Arms has. That is, until I thought of using a laser. I mean why would they (along with Kalibrgun, Daystate, FX, etc.) opt for a barrel band after all the R&D for accuracy if they knew it would affect POI at given air tube pressures? And for the love of God, why do some shooters think that the Cricket bullpup has the same problem when it has an even better barrel-to-scope mount system (in my opinion) than the above-stated guns? It doesn’t!
I am not saying that you need to work on your technique as I’m certain that you’re a great shot, but often, even after testing rifles from owners who had claimed that their barrel band may have been the cause of their POI problems, I saw that that wasn’t the case at all. And I proved to them by doing what I did, which was mount a laser to their barrel/shroud.
From my experience and lots and lots of practice and observation, I think the issue of consistent shifting of POI at different pressure levels is due to the change in recoil and or rifle-movement behavior during the shot cycle. The key to overcoming this problem is proper recoil management. Shooting technique must be one which allows for the rifle to exhibit the same movement from shot to shot across pressure ranges. As I’ve learned through experience with my S410, my old technique was ineffective at maintaining a strict degree of consistent recoil management. Needless to say, correct shooting technique, especially natural-point-of-aim (NPA) and trigger control, was a huge help in eliminating POI shifts. Moreover, all of a sudden, fairly loose, snug, and tight pellets started shooting to the same hole. Heck, it didn’t even matter whether the barrel was clean or had 6,000 pellets through it. The pellets went exactly where I aimed, and if they didn’t it was due to shooter error.
Try doing what I did and mount a laser to your rifle’s shroud and adjust the dot so that it is directly behind your crosshairs at your zero distance. If it does move when your air tube’s pressure rises and drops then at least you can confirm that is the culprit and rest easy knowing that you’re not crazy. 😀 If it doesn’t then something else is causing the issue. :winkn: Good luck!
Extremely common (with the POI nearly always moving as you described) and most of the ones I read are because there is some errant outside pressure on the barrel and then the pressure inside is changing as it empties. Many PCP’s do this a little bit. In some cases removing the band helps. Is anything touching the barrel anywhere now? Is it completely floating? Is anything under pressure when you loosen and tighten the stock? Can you post some pictures?
Air Arms including mine were notorious for that.
Why don’t you ship it to Earnest if you don’t figure it out. He will.
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I tuning my cricket step by step almost 2 years! My cricket is from second batch produced in Prague so there were some inaccuracy during producing them. But now it is a laser gun. I´m fully satisfied 😉 Just you have to learn a listen your gun and you will be ok. 😉