Lapping and Polishing barrels

The shroud isn't going to unscrew until you unscrew the airstripper. It might look like its part of the shroud but its separate and screwed onto the barrel. The shroud is just a tube, open on each end. I'll go take some pictures so you can see what I'm talking about. Once you remove this take some shots and see if the pellets are still spiralling.
 
After you unscrew the endcap and any moderators is this what yours looks like?

Now you have to unscrew the threaded piece. Theres not much to grab so wrap a rag around the threads and turn. Here's a pic of the air stripper.

Here's one of it removed from the shroud.

Now you can unscrew the shroud.

Here's a pic of the airstripper screwed onto the barrel without the shroud.

The easiest way to reassemble is to screw the airstripper into the moderator and endpiece then screw that whole assembly into the shroud and onto the barrel.
 
I just looked on AOA site and now I know what your shroud is like. If you can unscrew the endcap and the shroud still won't turn use a blowdrier or heatgun on the end of the shroud near the breech to loosen the locktite .You have to get the endcap unscrewed first as it is the airstripper and screws onto the barrel for proper alignment.
 
Here's how mine looks, it's a single piece


The only thing that can be removed is this end cap
20160303_184603_zpsger1cupl.jpg



That is the air stripper inside the shroud.
 
Its blue locktite which is removeable. Its alot easier to remove with heat applied. I was able to break mine free with a blow drier pretty easily. No need to put new locktite once removed. My hammer spring adjuster is really locktited (excuse my made up word) down . I've tried blow drier and a heatgun. Now I'm ready to take a torch to It.
 
Today I tested the groups at 50 yards with and without the shroud.

This first group is 8 shots with shroud at 50 yards


Tried some lubed pellets with shroud at 50 yards


This is shots with the shroud and air striper removed


This is 5 shots with air striper reinstalled on the barrel


Above results indicate that the shroud has some issue but have no idea what exactly is the issue and how can it be corrected.
 
Oh my god hsnmz! I'm going thru the exact same thing! I got a new barrel like a month ago because my first one had pitting on the inside, but it was very accurate. (I should have kept it!) So I'm thinking my new barrel just needs to be broken in because it hasn't been very accurate. I just received my Casio ex zr 1000 and filmed some groups and I couldnt believe the pellets were spiraling! Today I took the airstripper and endcap off and the groups were better. Then I put just the airstripper back on and my groups were awesome! The 25.4 were shooting really good and the 33.95 were better but some pellets still had a wobble. I started a thread on this in general airgunning- pellet spiraling. I think our pellets are getting damaged in the breech area where the brass meets the steel barrel. I've pushed a few pellets thru and the skirt gets caught in the groove there and takes a good amount of force to push past it. Check it out.