FX Lock this thread please- Discussed with Fredrik, there is no evidence of POI shift in FX barrel liner system

In the machine shop we had a saying.
If you made it, and it’s wrong, you made it wrong.

If you made it to print, you made it to spec; even if that is wrong.
I often wondered why they don’t hold the barrel via a pinch clamping arrangement.
A pinch clamp is like the shaft collar shown in picture, except the receiver is split at 12 o’clock and two or three socket head cap screws cause the barrel to be gripped 360°.

View attachment 429085

Because the pellet distortion caused by over tightening the barrel retention grub screws, dimpling the barrel through to the bore, will be nulled out by a tight choke :)
 
Here is my question everyone always talks about about a poi shift how much of a shift is it I never experienced it I was running cf liner but the 2 guys shooting impacts were are only using orings and haven't noticed it either so poi are we talking a inch plus or under that at say 50 yards
Do you mean that 1" shift at 50 yards is OK ?
 
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If you made it to print, you made it to spec; even if that is wrong.


Because the pellet distortion caused by over tightening the barrel retention grub screws, dimpling the barrel through to the bore, will be nulled out by a tight choke :)
I don’t understand your second comment. There is no dimpling with a pinch clamp. And the tenon that is at the breech end of the barrel is so thick a pinch will never squeeze the tenon down at all.
 
I have been using FX liners in my RTI’s since 2018 off and on. They are very consistent while they are in the gun. But you have to look at how it’s mounted. Yes is has one dumb little grub screw holding the slip fit with two orings end. But the whole barrel housing is in a shroud floating and vibrating with just the snug oring disc at the muzzle contacting the shroud. The shroud, because of how it’s mounted in the chassis, is as stout as a barrel. I can use my RTI with a FX liner as a walking stick and experience no POI shift due to abuse. So I wonder if let’s say an Impact or Maverick could have a full length shroud, from receiver/block all the way to the muzzle, would there ever be any issues. It could just be as simple as too many pieces and not letting that contraption of a barrel do its own thing in a safe constant environment.
 
I don’t understand your second comment. There is no dimpling with a pinch clamp. And the tenon that is at the breech end of the barrel is so thick a pinch will never squeeze the tenon down at all.

The fact that a pinch clamp does not dimple the barrel was my point. I was agreeing with you. I was joking about how a heavy muzzle choke would hide the effects of damage to the barrel, due to grub screws "pressing through" a thin soft barrel.

You asked why split clamps are not used. I suggested that while that would be superior, chokes made it possible to get away with grub screws.
 
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I have had zero POI shifts with my .177 M3.

I clean the barrel after each session at the range. I use an Otis .177 cable inserted at the muzzle. At the breech end I use a pair of lab tweezers to pull a WD40 soaked patch into the brass loop and then pull the patch through the bore and out through the muzzle. I continue this process with a new WD40 soaked patch until the patch remains clean.

The gun is then stored with the barrel wet.

At the beginning of the next session I repeat the same process with dry patches until no WD40 residual is present on the patch. I then air fire the rifle 4 times to clear WD40 from the air supply line to the pellet.

I then shoot two foulers and 3 sighters to ensure my POI equals my POA, which it has for the last 27 sessions.

I have never removed the barrel or shroud on this rifle and this is my third year of ownership.
 
You could ask him about the design flaw in Impact - oring stiction.
I discussed with Fredrik that perhaps as the new platform of Panthera etc. in which the liner is inside the plenum or the cylinder will help fixing the POI shift. But he really advised that in reality there is no issue of POI shift. Rather its just the dirty barrel that results into shift. He advised to clean the barrel.

That is why I shared his advise considering that it might be useful for other users. But I see from the responses of many seasoned airgunners here that they do not consider this shift to be due to dirty barrel.
 
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I have been using FX liners in my RTI’s since 2018 off and on. They are very consistent while they are in the gun. But you have to look at how it’s mounted. Yes is has one dumb little grub screw holding the slip fit with two orings end. But the whole barrel housing is in a shroud floating and vibrating with just the snug oring disc at the muzzle contacting the shroud. The shroud, because of how it’s mounted in the chassis, is as stout as a barrel. I can use my RTI with a FX liner as a walking stick and experience no POI shift due to abuse. So I wonder if let’s say an Impact or Maverick could have a full length shroud, from receiver/block all the way to the muzzle, would there ever be any issues. It could just be as simple as too many pieces and not letting that contraption of a barrel do its own thing in a safe constant environment.
It's great to know that your RTI is very consistent from time to time with the liner.

It reflects the same thing to me that the liners are very accurate and if we can keep them held into the gun with a more sturdy manner, there shouldn't be any issues of POI. I hope this may be the reason the FX introduced barrel tensioning kit to make the barrel and the liner more stable. Further the carbon fiber sleave inside the shell abd over the liner also help fix the issue.

Just like AZ who converts the liner into a sturdy barrel for installing in RAW and once it is done, RAW is further improved to a new level.
 
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I have had zero POI shifts with my .177 M3.

I clean the barrel after each session at the range. I use an Otis .177 cable inserted at the muzzle. At the breech end I use a pair of lab tweezers to pull a WD40 soaked patch into the brass loop and then pull the patch through the bore and out through the muzzle. I continue this process with a new WD40 soaked patch until the patch remains clean.

The gun is then stored with the barrel wet.

At the beginning of the next session I repeat the same process with dry patches until no WD40 residual is present on the patch. I then air fire the rifle 4 times to clear WD40 from the air supply line to the pellet.

I then shoot two foulers and 3 sighters to ensure my POI equals my POA, which it has for the last 27 sessions.

I have never removed the barrel or shroud on this rifle and this is my third year of ownership.
I agree, I too use the very similar approach and am also successful in reasonably holding the POI during the shooting sessions. Very small POI is there in such situation.

But as we go out to woods and expose the gun to jumps and jerks, the whole story changes.

However I understand that your further input may be very helpful.

When I bond the liner with some binding material into a metallic pipe and use it in Dalta Wolf are issues are vanished.

This reflects that the liners are great but perhaps the holding system needs improvements.

In the woods, if the barrel tensioner is installed, the issue of POI shift is reasonably handled.

It also reflects that if we hold the same liner in a better and more firm manners, the POI issue is addressed.
 
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When Impact is properly tuned, its a great shooter. I have just shared a group on another thread of this forum. I reproduce it here to show my liking. But I understand that everything has its pros and cons and we should accept all of this.

Screenshot_20221029_115516.jpg
IMG-20221029-WA0026.jpeg


With this tuning, my Impact out shoots me every time at the bench. IT IS A FACT.

But as it goes out in the woods, it shifts POI until I install barrel tensioning kit.

IT IS AS SIMPLE AS THAT.

So I understand that strgthening the barrel system is the fix that FX has already introduced.
 
Please note that I initiated this thread to share the views of the manufacturer and to seek the input and feedback from the users that can be very helpful for all of us.

I am happy that a lot of seasoned shooters participated in this thread with their 1st hand experiences.

I request now to close this thread here.

Any further comments on this cannot be productive as I understand.

We should respect each others views and experiences.

I have learned a lot from it and also am considering to fix where I have my own flaws.

At this phase when FX has just introduced a new great gun, it doesn't look appropriate to further lengthen this topic.

I hereby request the ADMIN to block this thread for any further comments. I personally don't know if I can myself lock this thread or not.

Let's enjoy shooting and improving our equipment and our skills.

I AM NOT GOING TO RESPOND TO ANY FURTHER COMMENTS ON THIS TOPIC IN THIS THREAD.

Happy shooting.

Bhaur
 
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