Are you referring to the one listed that a repair job was done with some welding to the bolt tube?Show pic of your bolt in its entirety. Where the piston is attaches the carrier especially. That would show the truth on how long the kali9 can last.
There is a user on here selling a broken kali9, as not broken. But that user shared plenty on reddit, so I know its broken. Hopefully no one bought it.
The carrier is the weakest on kali9, and its proprietary. If it breaks, there is a gunsmith that can fix it, but it is not 100% failsafe. Best is to buy replacement....but company went under.