FX Maverick Compact 30 cal
Regs 160/145
Power Wheel 6
The attached pictures were 859 fps AEA 45 gr pellets @ 40 yds, 5 shot groups. When I speak of POI shift, I'm not talking about shots being randomly scattered. I'm speaking about these groups as a whole shifting randomly and needing to rezero for this (see pics). In my case, my gun came shooting 840 fps and every once in awhile I would need to adjust the scope a couple of clicks and it was good for awhile. To be honest, I thought it was the cheap scope I had. Once I got a chrono, I started adjusting reg pressures for faster fps. After increasing speeds I needed to rezero much more often, just about every day. I replaced the scope, same issues. Then I started looking into this further and discovered other people were having the same problem. I pulled my barrel liner and it had 2 orings. I ordered additional orings from Utah Airguns and the cf sleeve. I put the cf sleeve on and lost my tight groups. I did not epoxy it, and it felt a little loose, not a tight play free fit. At that point I wasn't ready to glue my liner in, so I went back to the orings. I ended up using 10 orings evenly spaced with a double in the middle, using Teflon tape beside them to help keep them in place. Same result, good for a couple days and then off 1/2". I couldn't find a solution on the internet so I decided i needed to rethink this. Something has to be moving, but what.
Here's my theory I came up with. In a perfect world a perfectly straight barrel would be ideal. In this system the liner is between the jamb nut and the block. When tightening that jamb nut, if the distance between where the liner touches it and the block is less than the length of the liner by even a mm the liner has to arc. Under tension with an arc in it is force that could cause it to rotate slightly, or arc in the opposite direction. Either of these would change the poi. My jamb nut was fairly snug but not too tight. I loosened it to what I would describe as 1/4 snug. Finger tight then just barely tightened with a wrench.
It's only been a week now but it is shooting like a laser and I have had no need to rezero. I think the 10 orings is probably overkill, but i would use at least 3 or 4. I also think the cf liner may work if epoxied. I hope this helps someone, i know i spent countless hours trying to figure it out.
Full disclosure, I am not a certified technician, just a hillbilly striving for perfection.
Regs 160/145
Power Wheel 6
The attached pictures were 859 fps AEA 45 gr pellets @ 40 yds, 5 shot groups. When I speak of POI shift, I'm not talking about shots being randomly scattered. I'm speaking about these groups as a whole shifting randomly and needing to rezero for this (see pics). In my case, my gun came shooting 840 fps and every once in awhile I would need to adjust the scope a couple of clicks and it was good for awhile. To be honest, I thought it was the cheap scope I had. Once I got a chrono, I started adjusting reg pressures for faster fps. After increasing speeds I needed to rezero much more often, just about every day. I replaced the scope, same issues. Then I started looking into this further and discovered other people were having the same problem. I pulled my barrel liner and it had 2 orings. I ordered additional orings from Utah Airguns and the cf sleeve. I put the cf sleeve on and lost my tight groups. I did not epoxy it, and it felt a little loose, not a tight play free fit. At that point I wasn't ready to glue my liner in, so I went back to the orings. I ended up using 10 orings evenly spaced with a double in the middle, using Teflon tape beside them to help keep them in place. Same result, good for a couple days and then off 1/2". I couldn't find a solution on the internet so I decided i needed to rethink this. Something has to be moving, but what.
Here's my theory I came up with. In a perfect world a perfectly straight barrel would be ideal. In this system the liner is between the jamb nut and the block. When tightening that jamb nut, if the distance between where the liner touches it and the block is less than the length of the liner by even a mm the liner has to arc. Under tension with an arc in it is force that could cause it to rotate slightly, or arc in the opposite direction. Either of these would change the poi. My jamb nut was fairly snug but not too tight. I loosened it to what I would describe as 1/4 snug. Finger tight then just barely tightened with a wrench.
It's only been a week now but it is shooting like a laser and I have had no need to rezero. I think the 10 orings is probably overkill, but i would use at least 3 or 4. I also think the cf liner may work if epoxied. I hope this helps someone, i know i spent countless hours trying to figure it out.
Full disclosure, I am not a certified technician, just a hillbilly striving for perfection.
