No, it was done so it couldn't be removed in certain States where removable silencers are illegal apparantley. You can own a AK47 but not a seperate moderated air rifle.
There wouldn't be a lot of barrel thickness left if it was lathed out. As I said, chop it and start again. They are a bl**dy mess, believe me.
Best to chop the barrel and add a slip on silencer.
That will get the overall barrel length back up to around 17 inches.
It's a breakbarrel, so you need the mechanical advantage of a longer lever to make the cocking stroke easily manageable.
Been there, done that (see also Lyn Lewington's AR1 conversions)
Hacked and chiselled the ghastly thing off my Sabre, got down to the grooves, but left the barrel intact. I then modified an old custom silencer I had been given so it covered the grooves, it isn't really much of a silencer now, but looks much better and I still have the mechanical advantage for cocking.
Too many guns, or not enough time?
How deep are the grooves ? As per AB, why could you not turn that section of the barrel down until the grooves were removed - say it might be down to 12mm OD - and then sleave it back up with a bit of steel tube, bonded on with green loctite. Turn it down to match the rest of the barrel OD.
For sure you need a lathe, but it feels do-able if you wanted to retain the barrel length.
Always looking for any cheap, interesting, knackered "project" guns. Thanks, JB.
If the intention is to fit a good slip on mod, there would be no need to machine down in to the grooves,
simply turn it down until the surface is level with the rest of the barrel, & then cover the area with a slip-on mod.
Not perfect, but an option.
The area under the mod is a smaller diameter than the good section of the barrel
Turning it down will likely:-
1) produce a section that is too thin to be strong enough and / or
2) after the addition of a slip on moderator, leave you with a ridiculously long barrel
Hence my advice remains carbine it and add a slip on moderator