Carbon Fiber tubing for FX Impact liner and shroud mods.

[cwooten5]

Knifemaker! That’s awesome. (Your name that is) I have a coal forge in ground that I’m building waist high from a propane tank. Anyhoo;

I’ll begin with saying a have an impact X with pp tuned for 29.5 grain Neilson slugs. It is as accurate as it should be, however,

i built custom fishing rods from about 2010 to 2015, and even developed a prototype blank with hollow butt section and a solid carbon (about 45% off its length) tip section.

I read somewhere that the carbon “liner liner” for lack of better terms would eliminate all that slug fussiness we get with needing the exact (bumper) tune in the 950 FPS area, because apparently, that is a product strictly of harmonics. I scoured the Internet last night looking for the proper size, and while not perfect, I found a tubing that is .375 ID (my liner measures almost exactly 9mm, or .355) by .504” (my barrel sleeve I measure at 12 mm or .47” ID.

Now, not worried about the I.D., I can turn the tubing on the lathe and sand its exterior down from the .504 to .47. (PLEASE BE CAREFUL, 250 DEGREES WILL DESTROY THE RESINS)
Water cooling with a foam brush or rag is CRUCIAL.

SOURCE: Clearwater Composites standard modulus 3/8x1/2” tubing. Measures .375x.503 length is 36”, and it shipped for less than 50$.

However, I am concerned about the 20 thousandths that the carbon tube is bigger than the barrel liner. I think the epoxy way is the ticket, but with mixed results on here, now I’m skittish. I’ve heard it made to sound good, but if I end up the same, or God forbid WORSE, I really don’t have the money for a new barrel kit right now.

But I’ll share how I used to build up rod blanks for reel seats that were too big ID. You wrap tape around it, and there’s an auto centering effect, but tape ends somewhere, meaning barrel straightness could be compromised. I’d say maybe I mark the liner, and start and stop the tape in exactly the same places, exact same number of turns. Heck. Depending on tape, it may only take one complete turn, everywhere down the length of the liner. I guess we’ll see. 

Thinking out loud, input welcome. lol. I love these forums. The internet has SO grown the Airgun community!.

 

[qball]

I would not worry about using epoxy, all you have to do is leave it in the oven at 150 or melting point for the epoxy used and it will melt letting the sleeve slide right out. so there is less worry about the ID of the liner. The outside liner don’t have to be super tight fit either, it would be nice but I don’t think it has to be physically touching the barrel housing. Obviously exact sized that is pressed fitted to the barrel housing is ideal but hard to reverse like you said. The liner sleeve stiffen the liner a lot so it doesn’t have to be over done. Only way get even better results would be to forgot the housing and wrap the liner with carbon under tension with the TP attached and cure in oven……not an easy nor cheap process. 

 

[cwooten5]

Brother, my .25 caliber slug liner measured almost exactly 9 mm, or .355” on my digital calipers

 

[corny]

The liner doesn’t fit into a 9mm cf tube.

I used two cf tubes. 
10x9mm 12x10mm I bonded one into the other.

however I still had to sand the ID and OD to get a prober fit for the liner, and to be able to slide the whole thing into the barrel tube. 

 

[cwooten5]

So the carbon tube I bought was a 36 inch, so called 3/8x1/2.

With the ID, I built the liner up with 1 turn of masking tape with 1/2” or so gaps between them. The carbon OD was .504, and I sanded it down to .46., which fits fairly easily into the barrel sleeve. I cut the length to 23 3/8”, using the threaded tip as a gauge to stop the carbon sleeve while epoxy was wet. I’m prob half inch from the critical point at the transfer port end, But I’m not concerned about harmonics in a half inch of exposed liner. Today I will test it fairly well, but just shooting a little while on vacation, it seems like after a rezero, it’s consistent. This NEVER would have happened if I’d removed the liner before with the oring setup.

More to come!

Thank you all for the input…. Chris

 

[cwooten5]

 

[cwooten5]

•  Check out another thread me and knifemaker are conversing on. I reveal the source of the carbon fiber tubing, for 47$, which is sold as 3/8 x 1/2”. It measures .375 inside, and .504 outside. I sanded the outside To .46, and built up the liner about 20/1000s with one turn of masking tape, with small Gaps Between for epoxy to flow.
•  Seems consistent without re-harmonizing the tune with the valve spring bumper after Reassembling the liner and barrel so far, but will truly test today. My goal is to tighten groups and eliminate all the need to fine tune for slugs because of fussy harmonics 
• i don’t have many threads, it’s easy to find

 

[cwooten5]

Sorry actually same thread lol

 

[Stiglicius]

How actually is long CF sleve which is going over the 700 liner?

 

[Over_watch]

My understanding is that the STX and the Superior liners are both 8mm OD. Is that 8mm for .22 and .25 also? So getting an 8mm ID carbon fiber tube would be the first layer? Or I missed something since you mentioned 14mmx16mm thickness tubes. I almost bought a 16mm-20mm tube, but I realized that that 16mm is the barrel OD, and not the liner.

did this get answered? I was having the same question on my new Impact M3. is the OD of the .22 and .25 liners the same? I guess the question I am really asking is can I just swap the .22 line in my current barrel with a .25 and change the mag?

 

[Deadlands]

No, the OD of the .22 and .25 liners are different, but the ID of the barrel housings are the same. So the carbon fiber liner sleeves are different thickness but same OD to fill the space in the barrel housing. To change calibers you would need to change the mag, pellet probe, liner, carbon fiber liner sleeve, transfer port, and may have to open up the shroud exit hole and jam nut exit hole if going from smaller caliber to larger caliber.

 

[Over_watch]

ok thank you for that detail.

 

[erniebppr]

As a welder and fabricator with a somewhat grade of compulsive perfectionist i inmidiatly knew that the liner eaven with the sleeve will slam that whole liner up or down when fire because if you think that pushing a piece of lead 1/4 inch thick to 900fps requires bearly movement well,think again sunshine because will move and hard as you can't imagine, so I made grooves on the cf sleeve itself and was able to thread in by turning the sleeve until passes the thread then push slowly until the next o ring an I put 4 o rings and there was no movement of the barrel liner, all i got left was to shoot and see if i was crazy and will make no difference after all that work risking ruin something, or something amazing will happen if it actually works...guess what?...100% right not only shrink the groups by more than 2" is not a sensitive rifle anymore, never poi shift ANYMORE!!!! THATwas driving me close to give up the ******* thing and buy another brand until I did that, i very confidently bet money that any impact out there poi shift, if everything else is good i guaranteed 100% is the barrel movement inside the tubing, you have to make sure is all solid if you do that you eliminate poi issues and hold sensitive issues also, I have been blown away my m4 is shooting pellet on pellet at 85 yards and it was really 3 inch groups before sometime 2 inches but never less than that until i put o rings between cf sleeve and tubing and remember that will need lube and turning o rings until pass thread and repeat at least 4 o rings spread evenly you will not be disappointed if you do this, first time threading in the o rings one broke up and wasn't shooting straight at all,I took it out replaced the broken o ring ,and put it back on and then I got the crazy good results but it was 100% worth the time....i recommend this to everyone who owns an fx impact m4 you will not believe what it does to harmonics when you dampen up the vibrations is unreal.