Postino, I'm fumbling in the dark about this barrel.. Glad you pointed out that it's not a Lahti.
I'm no expert, but from pictures I don't think it looks like a Tikka eighter..
Here is a picture of the barrel attached to a Luger (second from the bottom). Please share your thoughts what it can be.
Btw. never had a lahti on my belt, but occasionally a Luger
Edit: it looks scratched/rough on that last picture due to the flash, it's actually smooth and is probably unused.