FX Crowns barrel is moving forward

[MEC17670]

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.

 

[MEC17670]

It’s just the liner moving… correct?

Yes

 

[MEC17670]

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.
View attachment 391284

Thank you,
I normally remove the complete shroud /barrel liner to clean it. I cross tighten the 4 locking grub screws when I reinstall it.
Are using you a ftlb or inchlb torque wrench?

 

[Revoman]

"Are using you a ftlb or inchlb torque wrench?"
Using an inchlb torque wrench. If I recall correctly, I used 18" pounds when reinstalling the assembly that has 4 grubs (C2). 24" pounds if only 2 grubs were used (C1).

 

[MEC17670]

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 was 978 , average 984. Sounded different , more of a poof, than a pop. Can't help but think, the seal I created is responsible for the velocity rise.
Bottom line , when doing maintenance on your fx guns not to forget those sleeve orings.

 

[Revoman]

Glad that you found and fixed the problem!

 

[MEC17670]

Glad that you found and fixed the problem!

Thank you, I hope all of us learned something through this journey.