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FX Impact Group POI Shifting

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I believe I have identified the issue. First, I cleaned the liner. To be clear, I’m calling the liner the part that has the lanes or rifling that the pellet engages. I removed the outer-shroud and then I removed the liner from the inter-shroud I used a combination of a bronze 22cal brush, Hoppes #9 followed by dry cotton patches and repeated the process three times. For testing/isolating purposes I left the shroud off and installed only the inter-shroud and liner back on the Impact and tightened the 3mm grub screw that holds the barrel assembly in place.

Next, I tested for results using JSB Diabolo Heavy 18.13gr at 45yrds. I shot five 5-shot groups and I’m now getting one ragged hole at 3/8” to 1/2” center to center. I then added the stock FX moderator and shot another five 5-shot groups. Those groups were also very tight, basically the same as without the moderator with a slight POI shift from the added weight. All is going good at this point. I added the outer-shroud with the moderator for a complete barrel assembly making sure everything was aligned and fitted correctly. I could tell right away that the outer-shroud was causing most of the accuracy issues as each group opened up with a couple of shoots touching and then a POI shift with the next 2 or 3 shots in the same hole on the target. The groups with the shroud installed was very similar to what I had be getting so it would appear that the outer-shroud is the cause of the POI shift.

I guess my next project will be to find a solution for the shroud causing unpredictable POIs. You guys have given me some things to try in regards on shroud upgrades and/or mods. I’ll report back as to what corrects the problem. Normally, I would just leave the shroud off but the it’s kind of loud without it.

Thanks to all who replied and I hope it helps someone in the future.
 
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@runningbull I am not familiar with the Impact and it’s shroud system, however, see if this is possible with your gun. I shot my gun without the shroud for a long time. I used a DonnyFL Tanto that screwed right onto the front of the barrel’s screw. A Larger LDC may work as well if the Impact has the clearance for it. It was very effective at keeping things quiet. 
If this seems unsightly to you, it can always be dressed with a Carbon Fiber tube. 
0479C189-2905-4842-8314-803EC2FDC0EF.1606517191.jpeg

 
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That is a new one to me. Was the shroud threaded properly on? Did you remove the shroud again to check that the stable POI was back? The reason I ask is that it might be a good idea to check barrel has not fouled up again as you did diagnose. Taking it off and shoot groups once more, would verify it. I had a FX crown gen 1 which barely lasted 50-100 shots before the barrel would foul again with lead after a fresh clean, and POI start to change again. That barrel work fine as long as the pellets are lubed.
 
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That is a new one to me. Was the shroud threaded properly on? Did you remove the shroud again to check that the stable POI was back? The reason I ask is that it might be a good idea to check barrel has not fouled up again as you did diagnose. Taking it off and shoot groups once more, would verify it. I had a FX crown gen 1 which barely lasted 50-100 shots before the barrel would foul again with lead after a fresh clean, and POI start to change again. That barrel work fine as long as the pellets are lubed.
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@tor47 you are spot on with verifying whether there is another shift without the shroud because of leading. I always run wet lubed slugs now and never get any of the past fouling issues, with very consistent groups.

@RunningBull if the groups tighten up after taking the shroud back off then it could be a couple of other common things associated with the nature of the shroud. Those being, the projectile could be experiencing a bit of turbulence from nearly clipping the outside rim of the LDC, or there could be a harmonic vibration commonly referred to as barrel whip. The first experiment can be checked by putting on a different LDC without the shroud. The second experiment done to change harmonic barrel whip has to be accomplished with tuning the gun for the tightest groups with the valve adjuster. If that doesnt help, the same can be accomplished with Limbsaver barrel de-resonator by moving it along the barrel to tighten groups.

https://www.amazon.com/LimbSaver-Sharpshooter-X-Ring-Barrel-Dampener/dp/B00Z6K10HQ
 
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I’ll try again tomorrow with the shroud removed to see if it’s cause by lead fouling or if the shroud is still causing the POI shift. This brings up a question, is the shroud glued onto the liner sleeve. If so, what glue should I be using, Loc-Tite Blue or something else?

I looked at Ernst Rowe’s carbon fiber shroud sleeve and his carbon fiber liner sleeve, $40 each. The liner sleeve eliminates the o-rings on the liner.
 
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I’ll try again tomorrow with the shroud removed to see if it’s cause by lead fouling or if the shroud is still causing the POI shift. This brings up a question, is the shroud glued onto the liner sleeve. If so, what glue should I be using, Loc-Tite Blue or something else?

I looked at Ernst Rowe’s carbon fiber shroud sleeve and his carbon fiber liner sleeve, $40 each. The liner sleeve eliminates the o-rings on the liner.
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This is why you need a solid barrel and robust attachment to the action. Shrouds, glue, locate, all reasons to avoid these kind of gimmicks if you're looking for precision accuracy. Couple of examples, RAW, Steyr. IMO, if you're interested in playing around with these adjustamatics, great, but don't expect them to compete with the best.

All of this just my opinion, and my wife says I'm always wrong.
 
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Once everything is set perfect never touch anything ever again and not even remove the barrel liner just use a pull through. Want another liner buy another Impact to do the other job set it perfect then leave it alone and so on then the next Impact and the next. Thats why a lot of us have so many Impacts here even in the same calibers too for different purposes.
 
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Once everything is set perfect never touch anything ever again and not even remove the barrel liner just use a pull through. Want another liner buy another Impact to do the other job set it perfect then leave it alone and so on then the next Impact and the next. Thats why a lot of us have so many Impacts here even in the same calibers too for different purposes.
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Yep, I'm one of them, 3 Impacts setup specifically for its intended projectile and purpose.

Lube pellets and slugs to minimize fouling, and leave the barrel assembly alone, never have a POI shift!
 
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I’ll try again tomorrow with the shroud removed to see if it’s cause by lead fouling or if the shroud is still causing the POI shift. This brings up a question, is the shroud glued onto the liner sleeve. If so, what glue should I be using, Loc-Tite Blue or something else?

I looked at Ernst Rowe’s carbon fiber shroud sleeve and his carbon fiber liner sleeve, $40 each. The liner sleeve eliminates the o-rings on the liner.
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I am not sure about what you mean about the shroud. It threads on the barrel nut. As long as you screw it on the threads, till it bottoms out it should stay there. There is no glue, or loctite there. I am just asking: Maybe the shroud was not completely threaded on? That would in case explain the POI shift, as it would move around. When you put it on, you have to make sure it enters the threads on the liner nut. You will feel a positive stop, when you have screwed it all in. 
 
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I had the same problem point of impact went all over terrible all of a sudden 1.5" groups . So i put about 20 patches some with barastol some clean until there was nothing else showing on patches they were spotless accuracy still all over 1.5" group at 32 yards so this evening i put my 22 cal brush down the barrel about 6 or 8 times then put it back together and shot 52 rounds and the hole was 3/8" just contnuous threw the same hole it was defintly lead fowling i am happy again. But my gun was a Dream Tac Compact
 
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