going a bit OT here, really, but guess it's OK, komrad, if we try to solve your problem
can't really see where the break is from the pics so i'm guessing it's at the junction between the front sight itself and the outer barrel holder of the front sight trunnion. if so, then your best bet (if you are not too OC about authentic looks) would be to super glue the broken parts together and then, to make sure it holds the load exerted by the upper handguard retainer ring, to mold and glue a strip of aluminum or thin steel sheet to the outer surfaces of the lower front sight trunnion. that sheet should hold the upper and lower parts of the front sight trunnion together.
three things need to be done before you do that:
1. strip the paint from the surfaces to be glued. this will ensure that the glue sticks to the metal, not the paint.
2. wrap the outer barrel in one layer of cellophane tape and then spray that tape with some silicone oil before gluing the parts together. this will ensure that the glue does not bond the front sight trunnion to the outer barrel.
3, buff or sand the outer surfaces of the lower sight trunnion (the part to which you will glue the metal strip) and the metal strip to give the glue a better surface to bond to.
this was done to komrad zT's rear sight trunnion's barrel junction when it broke.
the zinc alloy parts of the Kalash Krink were really not cast well. there are bubbles inside the cast parts and the formulation of the alloy itself, IMHO, is really low class.
you can use pioneer super glue or loctite. loctite has a new product line branded "Sumo" which is supposed to work better with metals such as zinc and aluminum that usually does not respond well to super glue types of bonding agents.
hope that helps, komrad RB