ERNEST ROWE’s Carbon Fiber STX Liner Sleeves keep my FX CROWN’s POI consistent!

[intenseaty22]

@ladwict I don’t want to hijack Joe’s thread with my old issues. If you watch my video embedded HERE you will see that I am aware of everything you mention there. Feel free to comment on my thread or my channel about this. I will just say that I did use the recommended JSB pellets, the ones you’d expect the gun to shoot. At 20 yards it was grouping like a shotgun. NONE of my other guns have done that from factory, none, not even my Springers. The gun was tuned with the help of an experienced tuner btw & while it improved, that POI was always an issue. 

 

[ladwict]

O.k. That is fine and makes a big difference. I watched your review and struggle you had . You solved this nicely and I second most of what you are saying. Well done ! I could see how the CF sleeve helped you with that particular barrel. Believe me the WC MK3 is one of the best bullpup concepts . Simple and straight forward. Hole in hole at 30 yards should be the norm ! Do not be misled though by the max power indications presented by FX in their specs. Therefore you would really need a power plenum like yours but then without the leaking. Did you try an other o-ring ?

succes !

 

[Khornet]

My 700 mm .22 Impact was making fine groups, but always in a slightly different place from day to day. So I installed a CF sleeve on the liner. Groups immediately went in the toilet, enough that I couldn't tell whether the zero had stabilized. The fit of the sleeve in the "barrel" (why call it that, I dunno) was much looser than with the O-rings, so a little Scotch tape at three points on the CF sleeve was applied. Groups improved, but not nearly back to what they were before I "fixed" things. Then I thought Duh! Of course the CF sleeve totally changed the harmonics. So I began changing one thing at a time....adjust valve, groups a little better, adjust more, groups worse, go back one step, then adjust hammer, groups a little better, adjust more, worse, go back one step, adjust regulator....bingo. Tight groups again, just at a different combination of settings than before, but still with some zero shift, just not as bad as before. So I broke down and got a much better scope. Now the zero is stable, groups are tight.

I'll bet that new liner O-rings and/or a better scope would have fixed this from the get-go, but it's the journey, not the destination. I learned a lot.

I'm not interested by a firearm for which I can't reload or otherwise tweak to get the best performance. I once took a year to get a 50-year-old service rifle to shoot well, but now it's a sub-MOA rifle. A 1943 GI 2-groove barrel. Likewise with airguns. The potential for perfection, and the pursuit of it, is the thing which draws me, frustrating though it may often be.

 

[ladwict]

If you have poi shift from 1 day to the other try tightening your barrel screw. ( where barrel gets into the action ) also make sure your shroud is not touching anything like the moderator that could “ clamp” it in different positions . Also check if velocity is not varying too much . Also check if you hold your rifle ( rectcle in yr. Scope) always the same ( canting ) 

 

[steve-l]

My problem going to the Rock West website was my VPN. The tube they offer is not so expensive. It is not only high modulus and super stiff, but it is a 64" long. Long enough to do two barrels. So the $137 price needs to be halved and at that price, it is competitive.

I also noticed that some folks are confusing this fix to the Crown' issue of a shifting POI, session to session. This tube mod will not fix that. That issue is caused because on the Crown the barrel assembly, including the shroud, is only supported at the breech end. It takes very little to disturb that enough to change the POI. Stiffening up the barrel will do nothing to remedy that, but a barrel band does fix it. Please note the Impact does not suffer this because the barrel is supported not only on the breech end, but mid barrel as well.

Don't get me wrong, I really like the CF tube thing. I think it is a good idea, but there are issues with the idea. The CF tube must fit the barrel and they don't. At least the ones I have found do not. The best fit I have found is a .25 barrel inside the Rock West tube. The barrel OD is 9mm (.355"). The ID of the Rock West tube is .375". That leaves .010" all round as an air gap assuming the tube and barrel is dead straight and concentric. (A big assumption.) So even on the .25 barrel, filling that gap is no simple task without leaving untold voids. Any other caliber, will be significantly worse. Will those voids create their own issues? Who knows. They certainly will not be the same one modified barrel to the next. I'm afraid this mod has not been thought through. Sourcing the correct size tube makes good sense before anything. Or perhaps wrapping a barrel with prepreg CF, vacuum wrapping and then using a professional autoclave to complete the cure is the best way to test the mod's effectiveness. In any case doing this correctly would be significantly more expensive.

One more point is that mtnGhost recommended to use Loctite 648. I took the trouble to look up the TDS of that product. You can find it here http://tds.henkel.com/tds5/Studio/ShowPDF/243%20NEW-EN?pid=648&format=MTR&subformat=REAC&language=EN&plant=WERCS

It states that at the .010"(.25mm) gap the product takes 170 hrs to fully cure and the cure will be less than 30% of it potential strength. It also states these figures are for steel. At the bottom left on the last page, they state the product is normally not recommended for plastic.

 

[Ranchibi]

Joe, awesome mod as usual! Like you said, making an already great shooting Crown into a better shooter is what you accomplished! Looks very "cool" too . My RAW has a carbon fiber sleeve on it's barrel and adds those attributes just as you said, rigidity/strength and reduces harmonics, a good thing with free floating barrels.

 

[ladwict]

One other factor not mentioned yet I believe is the diference in expansion coefficient between the liner and the carbon. When temperatures change I could imagine tension changing hence harmonics ..... The less (different) material touching the better in general. 

 

[intenseaty22]

That’s some ordeal you had with your WC .177.


I’ll make it easy, this previous post below has pictures of groups shot at different distances with my Crown .25. Before installing the CF sleeve:



https://www.airgunnation.com/topic/velocities-hot-or-not-with-fx-stx-superior-liners-and-diabolo-heavy-pellets/?referrer=1



Happy air gunning, and thanks intenseaty22!




Joe


Got it.

Joe, this right there is what it's all about. Making a great shooting gun shoot as close to perfect as possible. Nothing wrong with that. I read and commented on your linked post. You can't argue with that accuracy. Biggest problem I had with my WC was a constantly shifting POI despite having it shooting really well after all the tuning I did. I am pretty obsessive compulsive perfectionist so improving on a good thing is something I totally understand. However, for me, a gun as expensive as the WC can't be that finicky that requires so much walking around egg shells for it to do what it should do in the first place. 

 

[JoeKool]

Haven’t seen mention or details of the CF sleeve and or compression tensioning of the Crown with the light weight barrel system?

Is there such thing or need for one?

It would have to be mighty thick, don’t see where it would be feasible to do this. The brass locking nut in the design was touted to promote more rigidity over the first generation’s blued steel liner sleeves.

Haven’t heard of many issues with the superlight barrels, could be that the carbon fiber sleeves are just an upgrade geared towards earlier models.



2 cents



Joe

 

[JoeKool]

Joe, awesome mod as usual! Like you said, making an already great shooting Crown into a better shooter is what you accomplished! Looks very "cool" too

. My RAW has a carbon fiber sleeve on it's barrel and adds those attributes just as you said, rigidity/strength and reduces harmonics, a good thing with free floating barrels.

Thanks Ranchibi!



Hey, by the way Shane Kellar won the Extreme Benchrest of 2017 with this same model FX Crown .25 without any carbon fiber sleeve (they weren’t invented yet). So, the gun is definitely a goodie.

 

[Greenarrow]

Wow Joe! I don’t know how you came up with you did but YOUR TITLE implied that your POI wasn’t consistent before the liner. It’s your thread. I was only congratulating you on solving a non-issue then? 


As far as a backhanded compliment.... now you are implying something.


Enjoy my friend!

If I misinterpreted what you meant, my total bad. All good!!

No sweat on my end! No insults meant from me towards you either. You know we have similar tastes in air rifles too so I’m not gonna jab at fellow FX shooter.


My stuff is more FX old school. Less do-dads and do-hickeys for me to twist and mess up. Shoot, I can barely shoot straight let alone get a complex gun dialed in to shoot the hair off a gnats bum!



sincerely I’m happy it’s shooting better for you. These things ARE NOT cheap. I just hate reading about adding more , and to these things to get them shoot consistent.


Hang tough man!

 

[JoeKool]

Wow Joe! I don’t know how you came up with you did but YOUR TITLE implied that your POI wasn’t consistent before the liner. It’s your thread. I was only congratulating you on solving a non-issue then? 


As far as a backhanded compliment.... now you are implying something.


Enjoy my friend!

If I misinterpreted what you meant, my total bad. All good!!

No sweat on my end! No insults meant from me towards you either. You know we have similar tastes in air rifles too so I’m not gonna jab at fellow FX shooter.

My stuff is more FX old school. Less do-dads and do-hickeys for me to twist and mess up. Shoot, I can barely shoot straight let alone get a complex gun dialed in to shoot the hair off a gnats bum!

sincerely I’m happy it’s shooting better for you. These things ARE NOT cheap. I just hate reading about adding more

, and to these things to get them shoot consistent.


Hang tough man!

It’s great to discuss matters in civil fashion! Need more of that on the internet..



I view it like this.. My V8 doesn’t need a turbocharger, but... It sure would hall a$$ with one!



Soup’n up my airguns has become a fun hobby for me. Cheeper than sports cars.. lolololol 




All the best!



JoeKool

P.S. Those airguns are bad to the bone dude!!

 

[JoeKool]

One other factor not mentioned yet I believe is the diference in expansion coefficient between the liner and the carbon. When temperatures change I could imagine tension changing hence harmonics ..... The less (different) material touching the better in general.

Check this out ladwict??



https://www.airgunnation.com/topic/fx-crown-barrel-band-unnecessary-yet-necessary/?referrer=1



I sort of tested what you speak of, good point.

 

[steve-l]

Joe, I too have heard of no issues with the new barrel mount method. It is certainly better than the old set screw, but whether this corrects the session to session issue of POI shift, only time will tell. I don't think the difference in thermal expansion coefficients is an issue between the different materials because there is very little temperature variation in use. However, without mid-barrel support the barrel supported only at the breech is problematic, especially when we start hanging moderators on the end. I also do not know how persuasive the new barrel mount is in relation to the rest of FX's product line. I like the change and it should be everywhere.

I would also like to mention that there are two schools of thought on the subject of barrel whip or harmonics if you will. First school says that it isn't an issue as long as it's consistent. The second school says that it must be prevented for consistency. I think there are valid arguments in both camps. My question is "How valid is the issue in an airgun in the first place?" That said, what are we really fixing with a CF sleeve? I mean, I don't think it will hurt, but there is this thing called diminishing returns.

 

[ladwict]

I think the main thing fixed with the CF sleeve is the fact that when changing liners or fiddling around with them the original o-rings that could glide all over the tube are replaced by a sleeve that gives a more consistent vibe. Fixing the o-rings in place will do also a good job in this respect from my experience. ( 0,02 cents worth of duct tape) . On the other side like I said before the CF sleeve brings an other element into the equation that could cause harmonic issues....

 

[JoeKool]

Joe, I too have heard of no issues with the new barrel mount method. It is certainly better than the old set screw, but whether this corrects the session to session issue of POI shift, only time will tell. I don't think the difference in thermal expansion coefficients is an issue between the different materials because there is very little temperature variation in use. However, without mid-barrel support the barrel supported only at the breech is problematic, especially when we start hanging moderators on the end. I also do not know how persuasive the new barrel mount is in relation to the rest of FX's product line. I like the change and it should be everywhere.

I would also like to mention that there are two schools of thought on the subject of barrel whip or harmonics if you will. First school says that it isn't an issue as long as it's consistent. The second school says that it must be prevented for consistency. I think there are valid arguments in both camps. My question is "How valid is the issue in an airgun in the first place?" That said, what are we really fixing with a CF sleeve? I mean, I don't think it will hurt, but there is this thing called diminishing returns.

Well put. To answer your question, here’s what I believe. The carbon fiber sleeve makes the STX barrel system more like the solid steel smooth twist barrels on FX’s such as the Streamline and Royale in the day. They had full solid steel barrels and free floating which were just solid and held position better by design to be free floating. A one-piece thick steel barrel secured at the end which was inherently more stable. They did have droop issues from the weight as I recall though. As opposed to the original STX barrel system design which is part thin steel, “malleable rubber o-rings”, and a STX liner. The key difference being the “malleable rubber o-rings”. I believe that the , , , non-malleable Carbon Fiber Sleeve helps make the STX barrel more firm-positioned like the old smooth twists of yesteryear. Personally, free-floating barrels are not what I’d prefer on any airgun, I wish they all were made to be supported at the breech and at least the middle... But, I don’t design and build them. Take a break barrel springer for example if it is not designed well and has a wobble to its barrel the groups could be all over the place. Then take underlever springers with a fixed barrel that can’t move those tend to be very accurate. We could go on and on but this was just a $40 upgrade that I believe helped my ol’ 2017 Crown .25 be more consistent.



Thanks for the thought provoking comment steve-l!



Joe

 

[steve-l]

Joe, I too will be doing this CF tube mod. Like I said it cannot hurt and I now have a super new barrel. I bought a new Superior heavy and it shoots lights out. I think it is a great candidate for this. I really do believe that a barrel band is necessary though, but not a wimpy one. These are long barrels and banging them around , even lightly causes a POI shift. I have attached some photos of the one I am now using. It is from OHIO Airguns. It is my second one. The first split at the countersunk screws under tension. (Low density plastic.) I asked for another without holes and screws and he accommodated my request. I then drilled and tapped two stainless steel nut plates to make the bottle clamp. These spread the clamping load across the whole width of the clamp. So far, so good. Very solid. You can also see my home made moderator in the first photo.

 

[Ranchibi]

Joe, awesome mod as usual! Like you said, making an already great shooting Crown into a better shooter is what you accomplished! Looks very "cool" too

. My RAW has a carbon fiber sleeve on it's barrel and adds those attributes just as you said, rigidity/strength and reduces harmonics, a good thing with free floating barrels.

Thanks Ranchibi!



Hey, by the way Shane Kellar won the Extreme Benchrest of 2017 with this same model FX Crown .25 without any carbon fiber sleeve (they weren’t invented yet). So, the gun is definitely a goodie.

Joe, that's AWESOME! A friend sold a Crown to my other friend through me whose only PCP had been an Urban.....he is now ready to purchase an FX WC mkiii Sniper in .22..he is HOOKED shooting the best one can get! I shot his Crown....amazing guns for sure. Looking forward to shooting his Sniper when he gets it.

 

[mtnGhost]

My problem going to the Rock West website was my VPN. The tube they offer is not so expensive. It is not only high modulus and super stiff, but it is a 64" long. Long enough to do two barrels. So the $137 price needs to be halved and at that price, it is competitive.

I also noticed that some folks are confusing this fix to the Crown' issue of a shifting POI, session to session. This tube mod will not fix that. That issue is caused because on the Crown the barrel assembly, including the shroud, is only supported at the breech end. It takes very little to disturb that enough to change the POI. Stiffening up the barrel will do nothing to remedy that, but a barrel band does fix it. Please note the Impact does not suffer this because the barrel is supported not only on the breech end, but mid barrel as well.

Don't get me wrong, I really like the CF tube thing. I think it is a good idea, but there are issues with the idea. The CF tube must fit the barrel and they don't. At least the ones I have found do not. The best fit I have found is a .25 barrel inside the Rock West tube. The barrel OD is 9mm (.355"). The ID of the Rock West tube is .375". That leaves .010" all round as an air gap assuming the tube and barrel is dead straight and concentric. (A big assumption.) So even on the .25 barrel, filling that gap is no simple task without leaving untold voids. Any other caliber, will be significantly worse. Will those voids create their own issues? Who knows. They certainly will not be the same one modified barrel to the next. I'm afraid this mod has not been thought through. Sourcing the correct size tube makes good sense before anything. Or perhaps wrapping a barrel with prepreg CF, vacuum wrapping and then using a professional autoclave to complete the cure is the best way to test the mod's effectiveness. In any case doing this correctly would be significantly more expensive.

One more point is that mtnGhost recommended to use Loctite 648. I took the trouble to look up the TDS of that product. You can find it here http://tds.henkel.com/tds5/Studio/ShowPDF/243%20NEW-EN?pid=648&format=MTR&subformat=REAC&language=EN&plant=WERCS

It states that at the .010"(.25mm) gap the product takes 170 hrs to fully cure and the cure will be less than 30% of it potential strength. It also states these figures are for steel. At the bottom left on the last page, they state the product is normally not recommended for plastic.

638, not 648 (big difference). You also need to consider imperfections when selecting a sleeve's I.D. That Rockwest tubing spec is perfect for the .25 liners like I said.

 

[steve-l]

mtnGhost, It appears the 638 TDS has similar restrictions as the 648. Please check yourself. : https://tdsna.henkel.com/americas/na/adhesives/hnauttds.nsf/web/FB168836AB931A10882571870000D859/$File/638-EN.pdf

I think the tube is as good as we can find for the .25, but it is still a challenge to prevent any voids with whatever is used to fill the gap between the tube ID 3/8" (.375") and the barrel OD 9mm (.355"). I hesitate to think what the shipping cost will be for a 64 inch tube to Europe.!