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.
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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