Thank you everyone for all the help and comments and forgive me for the late response but this last month i have been very busy and only this past couple of days i managed to find time to adress all this.
I reached out to krale concerning the problem i had and they promptly sent a return label so that they could troubleshoot/fix this but it unfortunately happens that the shipping options were not to my liking so i ended up cutting the barrel myself.
Being a semi-auto there is a piston that slides around the outer part of the barrel so i could not just simply chop off the end because most of the lenght is needed to actuate the mechanism.
At the very end there is a groove to place a circlip (not needed for function but as an extra safety)
I figured i could cut a cone with a very steep angle with tangent radius to ease off turbulence so that i could clear the damaged rifling but could still leave the outer part intact
Concentricity between rifling and outer diameter was good (0.020mm) at different depths past the damaged section. This one was not deforming the pellet but was throwing it out of alignment on some lands which would impose an exaggerated pitch angle at muzzle. Value i measured was 0.04mm on the most damaged groove in relation to the rest.
I took 2 groups at 35m before rework and 1 after. Pellets were HN 14.6gr field target trophy power at 695fps 21joule /15.5ft-lbs @55bar (needs a lighter hammer and different spring to work in semi at this low energy)
The velocity loss with the 6mm shorter barrel was 5fps at this pressure.
The bad part is i may have to test all the pellets out again.
The good part is i actually enjoy the run as much as the finish.
I feel tempted to inspect my other barrels after seeing these results just out of curiosity and learning purposes.
But before i do i may end up either polishing or reworking the other end.
Once again thank you guys for all the guides, knowledge and opinions. helped out a bunch to make me climb another step!