What is indexing? Important? If so, how do I do it with a FX liner? Does this apply to other air rifles/firearms?
FX Is indexing your liner in the FX important?
- Thread starter Maizen
- Start date
I just slap in the liners, but as i have a thick DIY shroud made of several pipes of carbon fiber pipe, well these are not 100 % strait.
So my rifle can be a foot or two off at 50 M.
I index the carbon fiber shroud to make sure that's up, and then compensate with the scope rings.
So my rifle can be a foot or two off at 50 M.
I index the carbon fiber shroud to make sure that's up, and then compensate with the scope rings.
Upvote 0
Thanks Pysiths for the link. I have forgotten this old video of mine, 4 years ago.
Yes, indexing does work. Give it a try and you will see why. I believe this is one of the reasons why my Impact MK2 and Crown shoot so accurately and consistently ever since. Yes, Reg/HS balance is important and so is shooting the "right" projectile in each setup.
Have fun experimenting.
Air Rifle Pestings
Yes, indexing does work. Give it a try and you will see why. I believe this is one of the reasons why my Impact MK2 and Crown shoot so accurately and consistently ever since. Yes, Reg/HS balance is important and so is shooting the "right" projectile in each setup.
Have fun experimenting.
Air Rifle Pestings
Upvote 0
Not really if you ask me. HOWEVER, there are plenty of videos showing indexing does make some difference. BUT! There are variables in a stock FX barrel to make the tests useful at all. First and foremost there is simply zero chance you can eliminate how the orings are supporting the liner after each indexing. If you pull the liner out then you are done for, if you twist the liner in the barrel with pliers then there are less variables but no guarantee that Orings aren't twisted or compressed unevenly. Then there is the torque of the jam nut, most people don't use a descent toque wrench when tightening the jam nut when indexing. Some people use electric tape to fix the orings in place, it's much better but I still think it's a little inconsistent, I simply hate those orings in general.
IMHO, the only way to eliminate these oring variables is to epoxy on the carbon liner sleeve, biggest reason is so it will NOT change/move on how the sleeve supports the liner thereafter! I've tried indexing after the epoxied sleeve and it does move the POI tiny bit but the groups doesn't look much different so never tried it again.
IMHO, the only way to eliminate these oring variables is to epoxy on the carbon liner sleeve, biggest reason is so it will NOT change/move on how the sleeve supports the liner thereafter! I've tried indexing after the epoxied sleeve and it does move the POI tiny bit but the groups doesn't look much different so never tried it again.
Last edited:
Upvote 0
Let me share my thoughts about barrel indexing. I am no professional of course, but this is what make sense to me.
Is barrel indexing important to make your gun shoots accurately? Not exactly. Accuracy depends on the REG/HS setting and ammo size/weight for the speed your gun is tuned for. That is another topic.
Back to indexing. Assuming the gun is shooting accurately. By rotating the barrel/liner, different POI can be achieved. The purpose of indexing, in my opinion, is to find the highest point of impact the projectile hits on the target paper. This will enable your scope to have more elevation adjustments for longer ranges. That is all. It is beneficial to have more elevation clicks if you want to reach out further.
Take for an example, your POI at the lowest position after you have turned the barrel/liner and compare that to the highest POI. If you keep that liner position, then you will need to adjust your elevation turret in order to hit that highest POI position. You have now used up a few of your elevation clicks.
I hope that makes sense. To find the highest POI, you will need to rotate the liner/barrel and do several test shots to find that position. Mark it and lock it down.
In addition, if you use a moderator, your POI will be different and you will need to dial your elevation/windage to get to your zero again. So, does it make sense to do barrel indexing? Well, that is up to you. But for me, it was a very useful lesson to learn and understand how my guns work.
Cheers.
Is barrel indexing important to make your gun shoots accurately? Not exactly. Accuracy depends on the REG/HS setting and ammo size/weight for the speed your gun is tuned for. That is another topic.
Back to indexing. Assuming the gun is shooting accurately. By rotating the barrel/liner, different POI can be achieved. The purpose of indexing, in my opinion, is to find the highest point of impact the projectile hits on the target paper. This will enable your scope to have more elevation adjustments for longer ranges. That is all. It is beneficial to have more elevation clicks if you want to reach out further.
Take for an example, your POI at the lowest position after you have turned the barrel/liner and compare that to the highest POI. If you keep that liner position, then you will need to adjust your elevation turret in order to hit that highest POI position. You have now used up a few of your elevation clicks.
I hope that makes sense. To find the highest POI, you will need to rotate the liner/barrel and do several test shots to find that position. Mark it and lock it down.
In addition, if you use a moderator, your POI will be different and you will need to dial your elevation/windage to get to your zero again. So, does it make sense to do barrel indexing? Well, that is up to you. But for me, it was a very useful lesson to learn and understand how my guns work.
Cheers.
Upvote 0
Not only achieving highest poi, but keeping the projectile traveling true to the barrel, left and right. A 1/4 turn with my liner makes a big difference. I go for centered vs highest poi.
Upvote 0
Yes I agree. However, your POI is based on your scope adjustment with your elevation and windage when you did the zeroing before doing an indexing tests. Unless you reset your scope to zero for elevation and windage, the barrel indexing would not be true either way.
For me, I still go for the highest POI. Left and right can be adjusted with the windage afterward.
For me, I still go for the highest POI. Left and right can be adjusted with the windage afterward.
Last edited:
Upvote 0
My highest POI favors to the left, so I don't go that route. I turn my liner until I get it centered from left to right @ 50 yards on a calm day, then zero my windage. With no wind, I don't have to add windage from going from 50 out to 100. Seems to work for me. To many parts in these barrel systems.
Upvote 0
I had indexing spread of 6" at 40 yards, then I put in carbon fiber sleeve on my liner and indexing went away. As my linter was out, I rolled it on the glass and there was bow in the middle 1/16 of an inch, after installing sleeve liner was perfectly straight, POI shift always was gone after the install.
So my conclusion was, POI shift and indexing is side effect of liner not being straight.
So my conclusion was, POI shift and indexing is side effect of liner not being straight.
Upvote 0
My scopes have 50 MOA adjustments, but anyway I zero @ 50 Meters or 100 Meters.
Liner indexing I chose which is closer to my scope optical center.
But I also tried something else, what I learned - the full credit goes to thomasair
To explain pictorially, talking at least 10 shot groups, when you rotate/index the liner you will see the group is going around an imaginable centerpoint in a circle or oval really doesn't matter - but the shape of the group pattern rotate as well !!!
I chose the location where the shape of a group is more horizontal vs vertical and reset my scope to that position. For explanation follow the credit....
Just a hint, you to see the 10 group pattern shape you must work on indexing @ longer distance, but let say 100 Meters.
Liner indexing I chose which is closer to my scope optical center.
But I also tried something else, what I learned - the full credit goes to thomasair
To explain pictorially, talking at least 10 shot groups, when you rotate/index the liner you will see the group is going around an imaginable centerpoint in a circle or oval really doesn't matter - but the shape of the group pattern rotate as well !!!
I chose the location where the shape of a group is more horizontal vs vertical
and reset my scope to that position. For explanation follow the credit....Just a hint, you to see the 10 group pattern shape you must work on indexing @ longer distance, but let say 100 Meters.
Last edited:
Upvote 0
This is the ONLY way i could get my M3 to shoot consistently !!! My WHOLE barrel assembly...liner, Barrel tube , Carbon tubes ( 3 of ) and custom machined spacers... ALL permanently bonded to form 1 assembly.
The original setup from FX is IMO a "Joke"
Last edited:
Upvote 0
I met someone at UA who puts a printed spacer in at the TP end and then progressively fills the barrel housing with expanding glue. Puts the jam nut on with each dose of glue to keep it all aligned. No orings or CF. I guess that’s the Gorilla barrel.
Upvote 0
I have been exposed to a precision medical instruments assemblies, where some finicky stuff needed to be epoxied.
Digital epoxy feeding and sheit like that. We had an epoxy chemical engineer on board to investigate the best solutions. The money was not an issue...I suppose to design a robot for that project that holds and rotates the parts until curing.
I have learned that every epoxying (single or compound) is moving when curing.
Epoxying the CF to liner can give you convenience only but nothing to do with precision or may expect even worst results when the epoxy start pushing things aside in that small gap.
Whoever did it - All placebo...
Digital epoxy feeding and sheit like that. We had an epoxy chemical engineer on board to investigate the best solutions. The money was not an issue...I suppose to design a robot for that project that holds and rotates the parts until curing.
I have learned that every epoxying (single or compound) is moving when curing.
Epoxying the CF to liner can give you convenience only but nothing to do with precision or may expect even worst results when the epoxy start pushing things aside in that small gap.
Whoever did it - All placebo...
Upvote 0
I have a black line on my barrel for top dead center so it's easy to index after pulling the barrel off. When I was sighting in at 100 yards I was surprised how far left it was hitting. I had a good 50 yard zero but didn't have my barrel indexed correctly. I dialed in my scope for correct windage at 100y . But later I ran across another thread on indexing a fx barrel and it reminded me that's what the problem was. Anyway, it makes sense to me now .
Upvote 0
Not sure I understand this. How do you determine centered if not by highest POI? If I rotate my barrel and I find the highest POI, then I figure I've aligned the POI with the bore vertically. If instead for example I have the barrel installed with the POI at the 9 o'clock or 3 o'clock position in my indexing, then I would expect a windage difference at various distances which seems to be the point of indexing.
As an aside, I've deleted the after O-ring in the barrel lock nut (muzzle) and replaced it with teflon tape for a spacer, though it does make getting the index mark oriented properly a hassle.
Upvote 0