Poi shift In FX Impact

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IRBR

IRBR

Member
Feb 14, 2020
10
8
wales, Denmark
Hi Guys
I have a problem with FX impact M3
I found that my poi followed a repeatable pattern through the course of a fill
there isn't any contact between the barrel and air tube
barrel cleaned and scope parallax is ok ,scope rail and mount is tight enough and liner is indexed
ES is only 5fps in shoot steering(more than 50 shoots) and 5 shoots group is very tight(8~10 mm in 50m)
but group shift have clockwise pattern start from 12 to 3 then 6 and 9 and last 12 after zero in each of them
any one have a suggestion?
 
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That is the coolest POI shift I ever heard of. Here is what I would do. I would loosen the set screw that holds the barrel in then slide the barrel out. Then I would slide the barrel back in and right when the brass transfer port gets to the breech block, make sure it’s lined up perfectly and slides right in. If your whole gun was assembled and aired up incorrectly and your barrel is on a slight bind, that might explain some things.
 
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Gotta say, that's weird. Is this your observation from a single fill, or has it repeated through several cycles? I assume all groups were with the same pellet, and the rifle in the same position. If a one time occurrence, I would say it's changing conditions, that coincidentally showed that pattern. If it consistently does it, well, that's just very strange, and you have a magic rifle.
 
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Hi Guys
Thanks For Yours Tips
but i wanna add some additions info
i test in isolated environment
i use rest and rifle is level and bubble is in center
tank pressure range from 230 ~ 170 bar
woogie_man (yes and plenum and rest of rifle are completely aligned )
from 230 to 210 in 12o clock
210 to 200 in 3 o clock
200 to 190 in 6 o clock
190 to 170 in 9 o clock
and below them goes to 12
 
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Hi,
Did you get the solution . Pls update. Seems like I am also starting to see a shifting POI pattern in my M3 wrt pressure.
kavna said:
Hi Guys
Thanks For Yours Tips
but i wanna add some additions info
i test in isolated environment
i use rest and rifle is level and bubble is in center
tank pressure range from 230 ~ 170 bar
woogie_man (yes and plenum and rest of rifle are completely aligned )
from 230 to 210 in 12o clock
210 to 200 in 3 o clock
200 to 190 in 6 o clock
190 to 170 in 9 o clock
and below them goes to 12
Click to expand...
,
 
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Why don’t you give us some history of the gun- what internal mods have you installed, Ammo type, caliber, etc.

Me personally I noticed early on when shooting pellets, the groups are best with a full mag, and somewhere when the mag gets to be only a third full, groups slowly start to open up. I’ve found that depending on the tension of the internal spring inside the mag, it can cause pellets to tilt as the spring pressure forces the pellet against one side of the mags exit hole, and it gets worse as the mag empties as there’s less weight from the pellets.

Because of this, I try to stop shooting and refill the mag when it gets down to the last 10 or so pellets.

And if you’re using a pin style pellet probe and if this is going on with your mag, that pin probe exacerbates things.

Without you realizing this, the start of a full mag is in line with a gun freshly pressurized full, then as you cocky thru your mag, coincidentally your air pressure is dropping and you are more focused on the air pressure being the cause of impact shifts, when it could be a problem with your mag.

So like was suggested, rule the mag out by single loading, and if your shooting pellets stay with a pellet probe, not a pin style
 
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Whenever I removed my liner for cleaning, I wrap a layer of teflon tape and install the liner nut.
Very recently I got the barrel tensioner. And I lapped the liner "seat" into the nut. Also made a new 10 mm socket for my torque wrench, I want to know that I am torquing the liner nut consistently, in my case I set it to 1.7 Nm, which is the lowest value on my wheeler digital.
 
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If you’re talking about the first few shots after the gun has been resting, it’s a common problem. The first few shots are often at a lower speed due to sticking O-rings. Here’s a very long thread discussing it:

Tuning - FX Impact Mk2/M3 - slower first shot - no reg creep - quasi-scientific analysis

Hi guys, Welcome everybody. This is my first post here. I have a problem with my Impact Mk2 PP .30. The reg pressure is 145 bars. When I shoot shot after shot then my v0 is 260m/s. However, when the gun sits for a couple of hours then the first shot is 250m/s despite the exact same reg...
www.airgunnation.com www.airgunnation.com
 
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