FX Crowns barrel is moving forward

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Hey Folks,
A follow up on the moving barrel sleeve.
I got the correct size orings that fits over the block end of the sleeve and was surprised the size difference between the old orings and the new.
Noticeably different size. I'll post a picture as soon as I get some more new ones.
Not sure if it was wear and tear that created the size difference or the factory installed the wrong size, which I doubt.
The new kit comes with 7 in the pak, old one had 6 . As I only got 6 , I installed 6 new ones and 1 old one. The 7 the allows the locking nut to lock down more material.
With fingers crossed , I shot my usual 29 gr. Neilson slugs which normal flys out at an average of 970. First shot, came out a smoking 993 with the same tune. The low...
MEC17670 said:
Hey Guys and Gals,
My .25 crown is sliding forward an inch in 3 shots rasing h*ll with my shooting.
I have 6 orings degressed on the block side of the shroud nut. I've cleaned the interior of the block where the barrel assembly sides into, and still shoot my barrel towards the muzzle.
Any ideas on how to rectify it?
Thanks.
Click to expand...
I had the same problem. after 2-3 shots the barrel moved and pellets got stuck in the barrel . Easy fix add more o rings on the liner . There are 5 now try 7 or 8 that put more compression to the liner when you tighten it down . .
 
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MEC17670 said:
Hey Guys and Gals,
My .25 crown is sliding forward an inch in 3 shots rasing h*ll with my shooting.
I have 6 orings degressed on the block side of the shroud nut. I've cleaned the interior of the block where the barrel assembly sides into, and still shoot my barrel towards the muzzle.
Any ideas on how to rectify it?
Thanks.
Click to expand...
Is it the barrel or the shroud that's moving ?
If its the barrel then I would suggest fighting the 2 screws holding it
If its the shroud rings are worn
 
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Sharp Pog said:
I had the same problem. after 2-3 shots the barrel moved and pellets got stuck in the barrel . Easy fix add more o rings on the liner . There are 5 now try 7 or 8 that put more compression to the liner when you tighten it down . .
Click to expand...
Thanks , will do.
The schematics show the wrong size. I'm asking alot, do you happen to know the size ?
Thanks again.
Long_Gun_Dallas said:
Yeah, I'm confused.... I would have to put my first guess down as the shroud is moving, not the barrel. This will of course affect accuracy. Think more clarification is needed. Pictures and maybe some added drawings would be good.

Crowns have two different barrel types....
Click to expand...
No,the barrel is moving.
I put a mark on the barrel against the nut with
DennisB said:
Is it the barrel or the shroud that's moving ?
If its the barrel then I would suggest fighting the 2 screws holding it
If its the shroud rings are worn
Click to expand...
The liner inside the barrel /shroud unit is moving.
Thanks
 
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Here's a picture. That small black dot is where the barrel was up agaisnt the nut. This is after three shots. Istop because the velocity started dropping drastically. From 970 , to 748, to 640 fps. Next shot probably would have jammed a slug. This whole thing started when i was indexing.
81330.jpeg
 
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Scotty1 said:
It works like an elongated compression connector, works okay but doesn’t instill a ton of confidence.
Click to expand...
I think as long as you don't disturb ie indexing your ok. The orings are compress into the lands and grooves of the liner, when they are "older" they may not comform to the new location. My guess.
R0B said:
The FX exploded diagram lists 7 x O-ring 5,5x2 NBR 70 in .25 cal for the Crown Superlight
Click to expand...
 
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The brass nut in your pic tightens and compresses the O-Rings holding the liner in place, but it also needs the black outer shroud to aid in that (the part that threads into the cone piece).
The shroud threading onto the liner tube via the muzzle adapter (outer black tube) holds that in place via the 2 or 4 screws (2 for older and 4 for newer Crowns) that are within the receiver block.
It LOOKS like you have the 4 screw (newer) block. I used to torque mine so that I could reinstall the barrel assembly to the same spec every time. Alternating like you would when mounting a spare tire or rifle scope.
1695515208431.png
 
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Are you certain that you have the right liner inside of the shroud? If the liner is a 600mm and your shroud is made for a 700mm liner, then it will shift forward because there isn't enough hold in the brass nut and O-Rings. It will move forward without the muzzle stopping it.
If the shroud for example is for a 700mm and the liner matches, then I'd consider the block screws are loose.
 
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I’m with Revoman on torquing the four barrel lock screws. Take it another step and use dog tip grub screws.

If you want to for sure guarantee the barrel in its entirety doesn’t move forward, have a machinist cut two grooves the entire circumference where the grub screws tighten up on.

Something tells me maybe your inner o ring that the pellet probe seals to, may be too thick. You combine thst with tight fitting pellets/slugs and your pellet probe is pushing thst barrel forward
 
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Hey Guys,
Evidently, when I bought my Crown mk2 600mm. 25, the barrel sleeve, not the shroud, the barrel sleeve, had 6 orings locking it into the block via the locking nut on the shroud cone.
Reviewing what was happening with FX USA, we discovered that the set of orings come in a 7 pack. Bingo!
6 brand-new orings held until I disturbed thier grip by the indexing process.
Fx USA is sending me the 7 pack of orings as a warranty issue.
 
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