i assume you have a flat top. i am assuming that the front sit uses a set screw. i am also assuming that you have a carry handle.
snug the front sight on. turn the gun upside down on a glass surface, IE stove cooktop, coffee table or something perfectly flat.
the two towers of the front side should be touching the surface along with the two towers on the carry handle. if you only have three points touching, something is askew.